SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    3158, 7900, 7904, 8754, 8765, 8757, 8756, 
    8755, 8764, 8758, 8760, 8759, 8761, 
    8762, 7891
  )

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "4.76"
    },
    "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": 22,
      "rows_produced_per_join": 22,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "2.56",
        "eval_cost": "2.20",
        "prefix_cost": "4.76",
        "data_read_per_join": "57K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (3158,7900,7904,8754,8765,8757,8756,8755,8764,8758,8760,8759,8761,8762,7891))"
    }
  }
}

Result