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 (
    599, 600, 601, 602, 603, 604, 605, 606, 
    675, 676, 677, 911, 912, 914, 915, 916, 
    917, 918, 919, 920, 921, 922, 923, 924, 
    925, 926, 927, 928, 929, 930, 931, 596, 
    597, 672, 673, 674, 678, 679, 680, 880, 
    881, 882, 883, 890, 891, 892, 893, 896, 
    897, 898, 899, 900, 901, 902, 903, 904, 
    905, 906, 907, 934, 935, 937, 938, 939, 
    940
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00141

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "113.15"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "9.06"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 125,
            "rows_produced_per_join": 5,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "29.49",
              "eval_cost": "1.00",
              "prefix_cost": "30.49",
              "data_read_per_join": "20K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`cscart`.`cscart_categories`.`storefront_id` in (0,1)) and ((`cscart`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`cscart`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`cscart`.`cscart_categories`.`usergroup_ids`)) and (`cscart`.`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": [
              "cscart.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 12,
            "rows_produced_per_join": 9,
            "filtered": "15.10",
            "index_condition": "(`cscart`.`cscart_products_categories`.`product_id` in (599,600,601,602,603,604,605,606,675,676,677,911,912,914,915,916,917,918,919,920,921,922,923,924,925,926,927,928,929,930,931,596,597,672,673,674,678,679,680,880,881,882,883,890,891,892,893,896,897,898,899,900,901,902,903,904,905,906,907,934,935,937,938,939,940))",
            "cost_info": {
              "read_cost": "61.60",
              "eval_cost": "1.81",
              "prefix_cost": "104.09",
              "data_read_per_join": "144"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}