LEX was supposed to have 2 controllers if 1 of them were working radar. If they weren't working radar, only 1 was required. There just isn't the traffic need for more than 1.

There are many mornings around 6am that I depart airports where there are multiple air carriers departing before the tower opens. KAZO opens at 6am. I think there is only 1 controller then, and multiple aircraft departing.

When the tower is closed, you treat it as any other uncontrolled airport. The tower was undermanned that morning, but no one will ever know if the proper staffing would have prevented the crash.