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 = 2910 
WHERE 
  cscart_products_categories.product_id IN (
    357695, 350166, 351109, 351665, 351706, 
    352131, 353415, 353261, 353262, 353529, 
    355225, 355897, 356720, 349870, 351281, 
    352960, 354535, 356589, 357067, 358172, 
    353285, 353428, 355773, 356995, 359348, 
    353111, 353326, 353388, 353536, 354023, 
    354674, 355194, 356783, 357083, 359109, 
    349880, 350707, 352099, 354960, 350274, 
    350691, 350802, 351185, 353048, 353568, 
    353657, 353844, 358809, 358992, 349923, 
    350701, 351217, 353080, 353113, 353335, 
    354706, 355502, 357314, 357321, 350186, 
    350371, 355570, 356147, 352885, 352972, 
    353280, 354363, 354803, 350997, 354115, 
    354961, 356912, 350111, 351058, 353682, 
    353820, 359256, 349861, 350443, 351052, 
    351611, 355526, 350239, 350735, 353604, 
    355345, 355513, 358031, 350430, 351500, 
    351729, 352537, 353404, 353905, 353991, 
    355478, 355718, 357205, 357787, 350485
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00218

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "281.15"
    },
    "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": 100,
            "rows_produced_per_join": 100,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "21.15",
              "eval_cost": "20.00",
              "prefix_cost": "41.15",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`webmarco`.`cscart_products_categories`.`product_id` in (357695,350166,351109,351665,351706,352131,353415,353261,353262,353529,355225,355897,356720,349870,351281,352960,354535,356589,357067,358172,353285,353428,355773,356995,359348,353111,353326,353388,353536,354023,354674,355194,356783,357083,359109,349880,350707,352099,354960,350274,350691,350802,351185,353048,353568,353657,353844,358809,358992,349923,350701,351217,353080,353113,353335,354706,355502,357314,357321,350186,350371,355570,356147,352885,352972,353280,354363,354803,350997,354115,354961,356912,350111,351058,353682,353820,359256,349861,350443,351052,351611,355526,350239,350735,353604,355345,355513,358031,350430,351500,351729,352537,353404,353905,353991,355478,355718,357205,357787,350485))"
          }
        },
        {
          "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",
              "webmarco.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 100,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "100.00",
              "eval_cost": "20.00",
              "prefix_cost": "161.15",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        },
        {
          "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": 5,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "100.00",
              "eval_cost": "1.00",
              "prefix_cost": "281.15",
              "data_read_per_join": "29K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}