200NL: Yucky spot with TPTK

[TheDespot]

200NL FR

Hero ($197) is UTG with Ad-Kc

Hero raises to $9, MP ($201) calls, BB ($284) calls

Flop Ks-2c-10s (Pot: $28)
BB checks, Hero bets $20, MP calls $20, BB raises to $50, Hero?

First off, it was my third hand at the table so I had no reads or anything. And I was multitabling so I didn't reload after the blinds in time so please no "reload preflop" tips.

Anyways, in this spot I really thought about raising, calling, or folding. I put the MP player on some sort of spade draw though obviously I'm not positive. The question is what the BB has. I don't think he ever has air here. My problem was whether he could just be doing this with a weaker king than my own to define his hand or even a semi-bluffed spade draw. Of course he can also have K-10 or a set in which case I'm drawing pretty slim. A fold is clearly safe here but is it a little too weak? This is a pretty standard spot so what's the generally accepted way to go about playing this here?