Fix mysql query

[zhouzhuojie]

Fix error

{
"message": "cannot find flag entity types. err:Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key ASC' at line 1"
}

Looks like Order("key ASC") was not supported in gorm to mysql driver. Since we don't really care about the orders, so just a queryset query is enough