SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids, 
  product_position_source.position AS position 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 265 
WHERE 
  cscart_products_categories.product_id IN (
    10469, 10470, 10471, 10472, 10473, 10474, 
    10475, 10476, 10477, 10478, 10479, 
    10480, 10481, 10482, 10483, 10484, 
    10485, 10486, 10487, 10488, 10489, 
    10490, 10491, 10492, 10493, 10494, 
    10495, 10496, 10497, 10498, 10499, 
    10500, 10501, 10502, 10503, 10504, 
    10505, 10506, 10507, 10508, 10509, 
    10510, 10511, 10512, 10513, 10514, 
    10515, 10516, 10517, 10518, 10519, 
    10520, 10521, 10522, 10523, 10524, 
    10525, 10526, 10527, 10528, 10529, 
    10530, 10531, 10532, 10533, 10534, 
    10535, 10536, 10537, 10538, 10539, 
    10659, 10660, 10661, 10662, 10663, 
    10664, 10665, 10666, 10667, 10668, 
    10691, 10692, 10693, 10694, 10695, 
    10696, 10697, 10698, 10699, 10700, 
    10701, 10702, 10703, 10704, 10705
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00573

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "68.67"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "1.76"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 40,
            "rows_produced_per_join": 1,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "4.54",
              "eval_cost": "0.16",
              "prefix_cost": "4.70",
              "data_read_per_join": "6K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`gaseus`.`cscart_categories`.`storefront_id` in (0,1)) and ((`gaseus`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`gaseus`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`gaseus`.`cscart_categories`.`usergroup_ids`))) and (`gaseus`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "gaseus.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 110,
            "rows_produced_per_join": 1,
            "filtered": "1.00",
            "index_condition": "(`gaseus`.`cscart_products_categories`.`product_id` in (10469,10470,10471,10472,10473,10474,10475,10476,10477,10478,10479,10480,10481,10482,10483,10484,10485,10486,10487,10488,10489,10490,10491,10492,10493,10494,10495,10496,10497,10498,10499,10500,10501,10502,10503,10504,10505,10506,10507,10508,10509,10510,10511,10512,10513,10514,10515,10516,10517,10518,10519,10520,10521,10522,10523,10524,10525,10526,10527,10528,10529,10530,10531,10532,10533,10534,10535,10536,10537,10538,10539,10659,10660,10661,10662,10663,10664,10665,10666,10667,10668,10691,10692,10693,10694,10695,10696,10697,10698,10699,10700,10701,10702,10703,10704,10705))",
            "cost_info": {
              "read_cost": "44.00",
              "eval_cost": "0.18",
              "prefix_cost": "66.30",
              "data_read_per_join": "28"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "product_position_source",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id",
              "product_id"
            ],
            "key_length": "6",
            "ref": [
              "const",
              "gaseus.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 1,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.44",
              "eval_cost": "0.18",
              "prefix_cost": "66.92",
              "data_read_per_join": "28"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}