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 = 372 
WHERE 
  cscart_products_categories.product_id IN (
    6778, 6793, 7698, 8960, 9014, 10148, 
    10325, 10420, 10128, 6494, 6575, 6579, 
    6674, 6718, 6816, 7540, 7543, 10122, 
    10217, 6496, 6548, 6775, 6809, 10387, 
    6715, 6758, 6766, 6768, 6717, 6771, 
    6813, 6716, 6772, 6669, 6671, 6812, 
    7522, 6761, 6672, 7516, 11046, 11255, 
    11277, 10428, 6760, 7699, 10956, 11067, 
    10312, 10453, 6767, 6815, 7704, 7729, 
    10226, 10471, 10196, 7751, 10219, 10365, 
    10398, 10463, 11280, 6759, 10315, 7753, 
    6668, 6762, 6765, 6810, 7750, 10406, 
    10436, 10480, 10486, 10545, 11155, 
    11456, 6404, 6757
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00350

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "137.73"
    },
    "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": 144,
            "rows_produced_per_join": 144,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (6778,6793,7698,8960,9014,10148,10325,10420,10128,6494,6575,6579,6674,6718,6816,7540,7543,10122,10217,6496,6548,6775,6809,10387,6715,6758,6766,6768,6717,6771,6813,6716,6772,6669,6671,6812,7522,6761,6672,7516,11046,11255,11277,10428,6760,7699,10956,11067,10312,10453,6767,6815,7704,7729,10226,10471,10196,7751,10219,10365,10398,10463,11280,6759,10315,7753,6668,6762,6765,6810,7750,10406,10436,10480,10486,10545,11155,11456,6404,6757))",
            "cost_info": {
              "read_cost": "70.41",
              "eval_cost": "14.40",
              "prefix_cost": "84.81",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "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": [
              "softwarepirmam_hewadelivard_cscart_4.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 7,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "36.00",
              "eval_cost": "0.72",
              "prefix_cost": "135.21",
              "data_read_per_join": "22K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`storefront_id` in (0,1)) and ((`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids`))) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "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",
              "softwarepirmam_hewadelivard_cscart_4.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 7,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "1.80",
              "eval_cost": "0.72",
              "prefix_cost": "137.73",
              "data_read_per_join": "115"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}