[emptyshell]

I'd fold the turn here. It's unlikely two players are in there with 34, just because 34 is a rare combination to play. It's likely one of the two players has a high hand. Moreover, playing a set passively on the flop w/ two low cards out is a reasonable play.

You could have check-raised the flop, but leading out isn't bad, either. If you successfully check-raise the flop and get called, you're just on the border of being pot-committed and still might have a tricky turn decision. If you lead out, get raised, and then reraise, all your money will be in the middle, which is desirable on this flop.