You don’t need q.all_of (it doesn’t hurt, but is doing nothing extra for you). The search function itself supports multiple query criteria by passing multiple arguments.
app_tables.clockinoutsystem.search(Users=self.user_name.text,Clock_In_Start=clock)
At some point you also lost the tables.order_by ordering. If you still need that, it goes before any of the query parameters, e.g.:
app_tables.clockinoutsystem.search(tables.order_by('Clock_In_Start', ascending=False), Users=self.user_name.text)