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 
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') 
WHERE 
  cscart_products_categories.product_id IN (
    514, 1505, 1506, 1507, 1508, 1509, 1510, 
    1511, 1512, 1513, 1514, 1515, 1516, 
    1526, 1527, 1528, 1529, 1530, 1531, 
    1532, 1533, 1534, 1535, 1536, 3675, 
    3727, 3728, 3730, 3731, 5210, 5211, 
    5212, 5213, 5214, 5215, 5216, 5217, 
    5218, 5219, 5228, 5229, 5230, 5231, 
    5232, 5233, 5234, 5235, 5236, 7496, 
    7497, 7500, 7501, 7506, 7507, 7528, 
    7529
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00288

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.24"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "0.94"
      },
      "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": 0,
            "filtered": "0.54",
            "index_condition": "(`gaseus`.`cscart_products_categories`.`product_id` in (514,1505,1506,1507,1508,1509,1510,1511,1512,1513,1514,1515,1516,1526,1527,1528,1529,1530,1531,1532,1533,1534,1535,1536,3675,3727,3728,3730,3731,5210,5211,5212,5213,5214,5215,5216,5217,5218,5219,5228,5229,5230,5231,5232,5233,5234,5235,5236,7496,7497,7500,7501,7506,7507,7528,7529))",
            "cost_info": {
              "read_cost": "44.00",
              "eval_cost": "0.09",
              "prefix_cost": "66.30",
              "data_read_per_join": "15"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}