SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    187, 241, 2312, 188, 242, 206, 205, 1436, 
    1440, 2310, 189, 194, 208, 488, 2134
  )

Query time 0.00049

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": 23,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (187,241,2312,188,242,206,205,1436,1440,2310,189,194,208,488,2134)"
    }
  }
}