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 = 7340 
WHERE 
  cscart_products_categories.product_id IN (
    98456, 98476, 98477, 98478, 98479, 98480, 
    98481, 98483, 98484, 98490, 98492, 
    98759, 98769, 98770, 98771, 98772, 
    98897, 99066, 99508, 99512, 99516, 
    100480, 100481, 100484, 100485, 100486, 
    100700, 100701, 100702, 100703, 100704, 
    100705, 100706, 100707, 100708, 100709, 
    100710, 100711, 100712, 100713, 100714, 
    100715, 100716, 100717, 100718, 100719, 
    100720, 100721
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.01535

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "131.82"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "7.46"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 208,
            "rows_produced_per_join": 8,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "20.72",
              "eval_cost": "0.83",
              "prefix_cost": "21.55",
              "data_read_per_join": "21K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`nuie_scalesta_net`.`cscart_categories`.`storefront_id` in (0,1)) and ((`nuie_scalesta_net`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`nuie_scalesta_net`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`nuie_scalesta_net`.`cscart_categories`.`usergroup_ids`))) and (`nuie_scalesta_net`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "link_type",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "nuie_scalesta_net.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 117,
            "rows_produced_per_join": 7,
            "filtered": "0.76",
            "cost_info": {
              "read_cost": "2.33",
              "eval_cost": "0.75",
              "prefix_cost": "121.75",
              "data_read_per_join": "119"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (98456,98476,98477,98478,98479,98480,98481,98483,98484,98490,98492,98759,98769,98770,98771,98772,98897,99066,99508,99512,99516,100480,100481,100484,100485,100486,100700,100701,100702,100703,100704,100705,100706,100707,100708,100709,100710,100711,100712,100713,100714,100715,100716,100717,100718,100719,100720,100721))"
          }
        },
        {
          "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",
              "nuie_scalesta_net.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 7,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "1.87",
              "eval_cost": "0.75",
              "prefix_cost": "124.36",
              "data_read_per_join": "119"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}