Concrete sealer

Whatever product you are considering using, better make sure the moisture is not coming up from below, or the coating will fail. A known test is to lay plastic sheeting down on the slab, check in 24 hours.

I don't know of any coating that will perform well if the moisture is coming from below. You just can't stop it, regardless of it being epoxy or anything else.

Hopefully your original slab was poured over 6 mil plastic sheeting, if so, you're golden