2/5 Hand---Really Bad?

[MichaelOar]

I play limit 99% of the time, but I let two of my buddies talk me into playing a 2/5 blind NL game.

At the start of this hand, I have $800 and my opponent has $450.

3 guys limp, and I limp on the button with KQo. Blinds play too.

Flop is K 4 2 rainbow.

The blinds check to the second limper (this is his 3rd or 4th hand at the table--I have no real read, but the guy is a mid-40's white dude with a beer belly, sunglasses and a harley-davidson muscle t-shirt . . . ), who makes it $20. One guy calls, I ponder a raise, but ultimately decide that I would probably do well to keep the pot small. I call.

Turn is a K. Board is completely rainbowed now. The Harley guy now fires $75 into the pot. The flop-caller folds and the action is on me.

My thoughts here--
1. I don't think he flopped a set, as he just doesn't look like the type of guy who would bet a set in that spot--I figured he would try to trap if he had.
2. There are no real draws out there, so I figure he must have a made hand.
3. If he has K4 or K2, I'm in deep [censored], but I discount these hands based on the reasoning in #1.
4. If he has a worse king, he may lay it down if I jam.

I decide to just call, with the intention of calling any bet on the river and value betting if it is checked to me.

River is a Ten, and my opponent almost instantly moves in for $280. I take my time, think through the hand again, tip the cocktail waitress, and call. He says, "You win." I say, "then muck your hand." He apparently thinks there is a glimmer of hope that he is best, and tables 53o, and I take it down.

So, did I play this like a donk or what?
Thanks,

Michael