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 (
    1517, 1518, 1519, 1520, 1521, 1522, 1523, 
    1524, 1525, 1537, 1538, 1539, 1540, 
    1541, 1542, 1543, 1544, 1545, 2217, 
    2218, 2219, 2735, 2863, 2864, 3729, 
    3732, 5220, 5221, 5222, 5223, 5224, 
    5225, 5226, 5227, 5237, 5238, 5239, 
    5240, 5241, 5242, 5243, 5244, 5817, 
    5818, 5819, 6322, 6448, 6449, 7494, 
    7495, 7498, 7499, 7504, 7505, 7526, 
    7527
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00406

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.26"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "0.96"
      },
      "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 (1517,1518,1519,1520,1521,1522,1523,1524,1525,1537,1538,1539,1540,1541,1542,1543,1544,1545,2217,2218,2219,2735,2863,2864,3729,3732,5220,5221,5222,5223,5224,5225,5226,5227,5237,5238,5239,5240,5241,5242,5243,5244,5817,5818,5819,6322,6448,6449,7494,7495,7498,7499,7504,7505,7526,7527))",
            "cost_info": {
              "read_cost": "44.00",
              "eval_cost": "0.10",
              "prefix_cost": "66.30",
              "data_read_per_join": "15"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}