Livewell not draining

[ReelToy]

My live well in my 1986 23'cc does not drain when sitting the floor floods. Anyone know a good remedy. My transom is enclosed and overflow drain was put back in original place. Really do not care for square livewell in floor but not ready to do anything about it right now. Is there a checkvalve I could put in the overflow line or better question would it work. Or maybe a macerater pump in line.