It does look fishy & there's not alot of made hands in his range that take this line, could be 55, K9, 99, Kx - if he's bad.

The only thing I don't like is the board is paired & king is easily in your range and you've bet like you have one, so unless you are very aggressive he has to put you on a big pocket/trips alot of the time & has to think a bluff would be spew.
So it would be unusual for him to call bets on two streets with a draw (on a paired board) & then also to bluff lead river as well.
Also if he has a mid pp & wants to get to showdown cheaply donking for 45 is pretty much what hero would have bet anyway so he's not saving any money with that line and is risking a raise, so it doesnt seem likely enough
either.

So I probably wouldn't shove the river in this spot, as there are too many question marks.