ok, I hope I'm right..

There's 47 cards unseen and 7 of them will pair the board or give you quads.. so.. (40/47) * (36/46) = 66.6% chance of you not making a hand better than a flush.

This is assuming the turn doesn't hit it, adding 3 more outs on the river there's a 33% chance of making the better hand.

I'm probably wrong but I tried.