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 = 226 
WHERE 
  cscart_products_categories.product_id IN (
    34835, 37789, 39361, 34820, 40466, 40398, 
    40351, 38316, 39325, 40308, 39613, 
    38314, 37788, 36045, 39878, 39611, 
    39354, 39353, 39299, 39300, 39268, 
    38317, 39137, 39138, 39139, 39058, 
    38994, 39313, 37790, 38179
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00181

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "562.01"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 140,
            "rows_produced_per_join": 140,
            "filtered": "100.00",
            "index_condition": "(`ea201_diorama`.`cscart_products_categories`.`product_id` in (34835,37789,39361,34820,40466,40398,40351,38316,39325,40308,39613,38314,37788,36045,39878,39611,39354,39353,39299,39300,39268,38317,39137,39138,39139,39058,38994,39313,37790,38179))",
            "cost_info": {
              "read_cost": "198.01",
              "eval_cost": "28.00",
              "prefix_cost": "226.01",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "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",
              "ea201_diorama.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 140,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "140.00",
              "eval_cost": "28.00",
              "prefix_cost": "394.01",
              "data_read_per_join": "2K"
            },
            "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": [
              "ea201_diorama.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 7,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "140.00",
              "eval_cost": "1.40",
              "prefix_cost": "562.01",
              "data_read_per_join": "18K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`ea201_diorama`.`cscart_categories`.`storefront_id` in (0,1)) and ((`ea201_diorama`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`ea201_diorama`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`ea201_diorama`.`cscart_categories`.`usergroup_ids`)) and (`ea201_diorama`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}