SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    161, 162, 163, 164, 165, 166, 167, 168, 
    169, 170, 171, 172, 173, 174, 175
  )

Query time 0.00169

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": 15,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (161,162,163,164,165,166,167,168,169,170,171,172,173,174,175)"
    }
  }
}