I agree, it does seem a bit unneccessary to get youself in this position on the flop. Flat calling is optimal here, he is betting out enough to not give himself odds
to draw to the flush; raising him gives any 12+out hand the odds to just shove over the top (assuming he knows this but probably not....but still)
I would call, then if the turn is a club and
-he bets - you are more than likely beat and if you're not then you're drawing to all kinds of beat.
-he checks - could be a trap, if you bet he is calling with most of his range that beats you and folds all of those that don't so there's nothing to gain from betting, just check behind and be cheerful of a cheap showdown
if the turn is a non club and
-he bets small - probably drawing but if he's still denying himself the odds to draw then let him. Just call and call again on a non-club river. If the river's a club then you have to fold because either he had you beat all the way during the hand or he has caught up to his flush and you lose to every single hand in his range except weaker kings.
-he bets bigs - He's not drawing and thinks you might be, you are only beating the weak kings in his range, the weak kings do not constitute a large enough % to warrant calling here.
-he checks - Unless he's planning to check raise then you're way ahead, throw out a 2/3 to 3/4 pot raise to get calls from weak kings and drawing hands. Everything else probably folds and your single pair takes a nice pot.
You want to look deeper into a hand before making a decision to raise on any flop. A raise on any flop is leaving you pot commited if you are raising a hand you're willing to go all the way with. You need to process what can happen on the turn and river and decide what you will do with your hand as everything in front of you evolves. fwiw this is called "the line you take"
As you get better at the pokerz, the line you take in a hand is based on what your opponents have, then what your opponents think you have, and in the super highest limits what your opponents think you think they have. Ignore all that for now though and try to concentrate on how hands you play will progress based on the texture of the board, then add the tendancies of your opponent.
And you're never super happy about getting a single pair all in on any flop in a cash game for 100 big blinds, whether you got it in ahead or not.