SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    591, 588, 578, 579, 566, 554, 551, 552, 
    548, 542, 543, 536, 377, 598, 599, 604, 
    605, 606, 607
  )

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": ["parent"],
      "key": "parent",
      "key_length": "3",
      "used_key_parts": ["parent_id"],
      "rows": 19,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (591,588,578,579,566,554,551,552,548,542,543,536,377,598,599,604,605,606,607)"
    }
  }
}