Villain is a donk, so when he min 3b I'd say his most likely hands are KK+
some of the less likely hands are AJ+ and TT-QQ
and air some of the time

on the flop I felt that since he instapotted it, he probably had AK, QQ, KK or AA and KQ once in a blue moon
I had 1/6 chance to stack him on the turn, so if you do the math it's 15.50 to win a $120 pot so my flop call should have positive expectation
shoving flop is out of the question, he never folds whatever he bets full pot with (especially given that he min3b)
calling turn is also out of the question that card didn't really help us

Full Tilt No-Limit Hold'em, $1.00 BB (6 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

BB ($213.70)
UTG ($100)
Hero (MP) ($113.25)
CO ($63.60)
Button ($134.95)
SB ($103.70)

Preflop: Hero is MP with A, 2
1 fold, Hero bets $3.50, CO raises to $7, 3 folds, Hero calls $3.50

Flop: ($15.50) K, 9, Q (2 players)
Hero checks, CO bets $15.50, Hero calls $15.50

Turn: ($46.50) A (2 players)
Hero checks, CO bets $41.10 (All-In), Hero folds

Total pot: $46.50 | Rake: $2.30

how do you like it?