Call down. Pot is large, you probably have outs and there's a chance he's doing this with JJ-KK. While you may be drawing dead to a straight or slim to a set it's usually two pair. Raise the river if the board pairs, hoping to counterfeit him and fold to a 3-bet which would mean he got his full house.

(Most players with a made two pair or straight on the flop would slowplay and pop the expensive street, but since it's 2-5 spread and doesn't change on the bigger streets, that leads me to believe the 2 gave him two pair or a set. Or he just doesn't realize he would have gotten similar value out of 3-betting the flop.)