I'm not sure if it's on all android phones but: under settings you find your model # and tap on it 7 times to turn on developer mode. Once that's done there should be an option somewhere (I think under display maybe) to keep your screen from going to sleep IF it's plugged in charging. So there's a little bit of a catch to it.

I was recommended the stay alive app too though: https://play.google.com/store/apps/details?id=com.synetics.stay.alive&hl=en