Muck it. The guy potting it into you is basically representing some kind of made hand (because flop is drawless) and you are 30/70 underdog at best (if he has only a piece of it) or drawing dead if he flopped a monster set. Not good spot to chase overcards. Mucking unimproved overs against reasonable pressure is "standard book ABC" play.

However, that donk-betting can be exploited and bring some more value if opponent is prone to lead into a raiser with large variety of hands...

If he donk-bets every piece of flop&draw trying to push you off, you can try to smooth-call him on flop with overpair and pull the trigger on turn (if you have position). If he often folds to your flop-raises (when you are legit, like overpair ot tptk) then you can pick that read and consider to raise or checkraise him with air. But doing it without solid read is just not a solid poker

BTW...
That restaurant-owner (I can't remember his name) from High Stakes Poker EP6 did that stuff beautifully, when he checkraised his AQ against Nassirei's bet. Few hands later he made moderate hand, pair of tens from his AT and check-called two huge bets from the same player and dragged big pot when Nassirei mucked his Ace high junk. Reads