[10NL] A3s...NFD on flop

[Cobra_1878]

Villain is 29/28/10 over 70 hands. Att to Steal in LP, 55%, 64% on button. Fold to 3bet, 83%. Cbet 67%.

BB - 42/27/0 over 34 hands.

PokerStars - $0.10 NL (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

MP: $14.01
CO: $14.09
BTN: $10.15
Hero (SB): $10.40
BB: $6.15
UTG: $10.39

Hero posts SB $0.05, BB posts BB $0.10

Pre Flop: (pot: $0.15) Hero has 3 A

fold, fold, fold, BTN raises to $0.20, Hero calls $0.15, BB calls $0.10

Flop: ($0.60, 3 players) K 4 9
Hero checks, BB checks, BTN bets $0.40, Hero raises to $1.40, fold, BTN raises to $5.00, Hero ???

I should have 3bet pre here right? Flat calling is pretty bad.

Now we got to the flop and hit pretty much what we were looking for. I c/r (is it better to just call here?) and he decides to 3bet, a pretty big 3bet at that. Given villain is relatively unknown, do I fold here and wait for a better spot or get it in?