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 (
    10965, 10985, 11005, 11027, 11047, 11067, 
    11089, 11111, 11133, 11153, 11173, 
    11195, 11215, 11237, 11259, 11279, 
    11299, 11320, 11813, 11819, 11825, 
    11831, 11838, 11844, 11851, 11869, 
    11887, 11909, 11929, 11936, 11940, 
    11944, 11951, 11958, 11959, 11960, 
    11961, 11962, 11963, 11964, 11965, 
    12030, 12031, 12032, 12033, 12034, 
    12035, 12036, 12037, 12102, 12116, 
    12118, 12132, 12146, 12160, 12174, 
    12188, 12202, 8203, 8214, 8215, 8216, 
    8217, 8218, 8205, 8206, 8207, 8208, 
    8209, 8210, 8211, 8212, 1154, 3315, 
    6843, 3318, 3687, 5076, 6840, 4691, 
    3071, 513, 3505, 3319, 3306, 3296, 6841, 
    6846, 1172, 1173, 4917, 4918, 6962, 
    6966, 6967, 6965
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00419

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "69.08"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "2.06"
      },
      "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": 2,
            "filtered": "1.17",
            "index_condition": "(`gaseus`.`cscart_products_categories`.`product_id` in (10965,10985,11005,11027,11047,11067,11089,11111,11133,11153,11173,11195,11215,11237,11259,11279,11299,11320,11813,11819,11825,11831,11838,11844,11851,11869,11887,11909,11929,11936,11940,11944,11951,11958,11959,11960,11961,11962,11963,11964,11965,12030,12031,12032,12033,12034,12035,12036,12037,12102,12116,12118,12132,12146,12160,12174,12188,12202,8203,8214,8215,8216,8217,8218,8205,8206,8207,8208,8209,8210,8211,8212,1154,3315,6843,3318,3687,5076,6840,4691,3071,513,3505,3319,3306,3296,6841,6846,1172,1173,4917,4918,6962,6966,6967,6965))",
            "cost_info": {
              "read_cost": "44.00",
              "eval_cost": "0.21",
              "prefix_cost": "66.30",
              "data_read_per_join": "32"
            },
            "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": 2,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.52",
              "eval_cost": "0.21",
              "prefix_cost": "67.02",
              "data_read_per_join": "32"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}