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 = 344 
WHERE 
  cscart_products_categories.product_id IN (
    908, 3090, 2752, 1143, 2559, 2822, 2253, 
    2751, 2255, 2927, 2729, 3140, 1542, 
    3026, 853, 1540, 1544, 2736, 4887, 2251, 
    2252, 2254, 2869, 3174, 2877, 2788, 
    855, 2795, 5130, 2936, 2792, 3159, 3021, 
    3373, 3011, 2760, 3060, 2880, 2268, 
    3014, 3404, 3366, 3160, 3023, 3099, 
    2800, 2860, 3102, 2775, 2767, 2562, 
    3548, 5151, 2786, 3408, 3744, 2733, 
    3359, 5126, 5133, 2759, 5137, 3375, 
    3517, 5143, 8696, 8243, 8617, 8570, 
    8703, 7873, 7871, 7874, 9872, 10455, 
    8709, 8885, 7879, 8614, 8757
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00354

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "227.01"
    },
    "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": 180,
            "rows_produced_per_join": 180,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (908,3090,2752,1143,2559,2822,2253,2751,2255,2927,2729,3140,1542,3026,853,1540,1544,2736,4887,2251,2252,2254,2869,3174,2877,2788,855,2795,5130,2936,2792,3159,3021,3373,3011,2760,3060,2880,2268,3014,3404,3366,3160,3023,3099,2800,2860,3102,2775,2767,2562,3548,5151,2786,3408,3744,2733,3359,5126,5133,2759,5137,3375,3517,5143,8696,8243,8617,8570,8703,7873,7871,7874,9872,10455,8709,8885,7879,8614,8757))",
            "cost_info": {
              "read_cost": "83.01",
              "eval_cost": "18.00",
              "prefix_cost": "101.01",
              "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",
              "softwarepirmam_hewadelivard_cscart_4.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 180,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "45.00",
              "eval_cost": "18.00",
              "prefix_cost": "164.01",
              "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": [
              "softwarepirmam_hewadelivard_cscart_4.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 9,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "45.00",
              "eval_cost": "0.90",
              "prefix_cost": "227.01",
              "data_read_per_join": "28K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}