Hello,
First of all I do not like that 3bet. After 53 hands UTG seems to be a tight player, therefore his range is tight and ATs would do better when just called, specially since you have a fish on the BB who might join seeing the pot with basically any two cards and you will have position on both players and UTG will have the worst postion and will often fold bottom of his calling range on the flop.
I'll give him something approx 14% open from UTG, which gives this range: 77+, A7s+, K9s+, QTs+, JTs, ATo+, KJo+, QJo
After removing some hands that he folds to a 3bet we have 7,39%: 88+, ATs+, KJs+, QJs, JTs, AQo+
Therefore he would fold approx 48% of his range, if you want to take the pot now then you would need 66% folding equity. And ATs doesn't play well vs his calling range. If you hit an A it's often dominated by a better kicker of villain.
As played postflop you've got 12 cards, that improve your rage and most of the time give you nuts. After the cbet I can see him call with all his range specified above and it gives you such odds:
Board: K♣Q♦7♦
Equity Win Tie
MP2 48.82% 46.87% 1.95% { 88+, ATs+, KJs+, QJs, JTs, AQo+ }
CO 51.18% 49.23% 1.95% { AdTd }
If you bett the turn I can see him fold weak pp, QJ, AT,some of AQ combinations: AhAs, AhAc, AsAc, KdKh, KdKs, KhKs, QhQs, QhQc, QsQc, AhKh, AsKs, AhQh, AsQs, AcQc, KhQh, KsQs, AhJh, AsJs, AcJc, KdJd, KhJh, KsJs, JhTh, JsTs, JcTc, AhKd, AhKs, AsKd, AsKh, AcKd, AcKh, AcKs, AsQh
Equity before the turn cbet:
Board: K♣Q♦7♦ 4♥
Equity Win Tie
MP2 65.72% 63.62% 2.09% { 88+, ATs+, KJs+, QJs, JTs, AQo+ }
CO 34.28% 32.19% 2.09% { AdTd }
Equity after the turn cbet:
Board: K♣Q♦7♦ 4♥
Equity Win Tie
MP2 67.89% 67.38% 0.52% { AhAs, AhAc, AsAc, KdKh, KdKs, KhKs, QhQs, QhQc, QsQc, AhKh, AsKs, AhQh, AsQs, AcQc, KhQh, KsQs, AhJh, AsJs, AcJc, KdJd, KhJh, KsJs, JhTh, JsTs, JcTc, AhKd, AhKs, AsKd, AsKh, AcKd, AcKh, AcKs, AsQh }
CO 32.11% 31.59% 0.52% { AdTd }
As you see it doesn't change much and I do not think I like to cbet the turn here. However a bet around 1/4 of the pot could still be profitable, 12 cards give us nuts, so 12/46 = 26%. And when you hit your draw you have a bigger pot, if you hit for 9bb the pot on the river would be 55,5bb and you would get more value from a 1/2, 2/3 bet on the river than if you didn't hit the turn. This is creating more variance in your game, but also gives more profit.
As played bet on the river makes him fold only JT, AT and AJ here and makes him call 86% ofthe time and beat you always.
All in all I like cbet flop, cbet turn and check back river (unless you hit your draw) or cbet flop, check back turn and river.
