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 (
    82071, 82118, 82073, 82038, 149042, 
    82061, 81948, 82101, 82009, 81647, 
    82133, 82103, 81737, 81655, 82104, 
    81704, 81826, 81863, 81741, 81860, 
    81702, 82072, 81634, 81657, 81739, 
    81625, 82115, 81776, 82074, 81611, 
    81862, 81627, 82114, 82069, 81817, 
    81773, 81636, 81812, 81624, 81806, 
    82099, 82052, 81756, 81816, 82096, 
    81814, 81747, 81768, 82116, 82095, 
    81672, 81764, 81765, 81762, 81766
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00144

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "89.09"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "link_type",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 55,
            "rows_produced_per_join": 55,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "12.09",
              "eval_cost": "11.00",
              "prefix_cost": "23.09",
              "data_read_per_join": "880"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`webmarco`.`cscart_products_categories`.`product_id` in (82071,82118,82073,82038,149042,82061,81948,82101,82009,81647,82133,82103,81737,81655,82104,81704,81826,81863,81741,81860,81702,82072,81634,81657,81739,81625,82115,81776,82074,81611,81862,81627,82114,82069,81817,81773,81636,81812,81624,81806,82099,82052,81756,81816,82096,81814,81747,81768,82116,82095,81672,81764,81765,81762,81766))"
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "webmarco.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 2,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "55.00",
              "eval_cost": "0.55",
              "prefix_cost": "89.09",
              "data_read_per_join": "16K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`webmarco`.`cscart_categories`.`storefront_id` in (0,1)) and ((`webmarco`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`webmarco`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`webmarco`.`cscart_categories`.`usergroup_ids`)) and (`webmarco`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}