SELECT 
  id_path 
FROM 
  cscart_categories 
WHERE 
  category_id IN (
    1, 16, 24, 38, 46, 119, 122, 123, 206, 238, 
    249, 261, 306, 327
  )

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["category_id"],
      "rows": 14,
      "filtered": 100,
      "index_condition": "cscart_categories.category_id in (1,16,24,38,46,119,122,123,206,238,249,261,306,327)"
    }
  }
}