SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    3718, 3359, 3360, 638, 3355, 558, 3362, 
    3358, 3361, 3357, 3356
  )

Query time 0.00025

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": 18,
      "filtered": 100,
      "index_condition": "cscart_categories.parent_id in (3718,3359,3360,638,3355,558,3362,3358,3361,3357,3356)"
    }
  }
}