SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    10446, 10438, 10444, 10443, 10441, 10439, 
    10437, 10447, 10440, 10442, 10398, 
    10445, 6328
  )

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "14.23"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 33,
      "rows_produced_per_join": 33,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "7.63",
        "eval_cost": "6.60",
        "prefix_cost": "14.23",
        "data_read_per_join": "195K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (10446,10438,10444,10443,10441,10439,10437,10447,10440,10442,10398,10445,6328))"
    }
  }
}