SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    1937, 1938, 1939, 2579, 2580, 2583, 2584, 
    2585, 2586, 2601, 9929
  )

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "6.22"
    },
    "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": 13,
      "rows_produced_per_join": 13,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "3.62",
        "eval_cost": "2.60",
        "prefix_cost": "6.22",
        "data_read_per_join": "77K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (1937,1938,1939,2579,2580,2583,2584,2585,2586,2601,9929))"
    }
  }
}