Back before the unity version (in the 3.x days) there was a controls.txt file but that went away when we introduced key rebinding in the unity version (first official release of that was 4.0, back in 2010).
But the bindings are stored in a file, so if you look in:
"C:\Program Files (x86)\Steam\steamapps\common\AI War Fleet Command\RuntimeData\inputbindings.dat"
(unless you're not using the C drive for it, or some other path difference)
You'll see a list of all the bindings and what's bound to them. That's what the game actually uses (it's updated when you change them in game). Unfortunately it's a bit of a pain for a human to read but perhaps it will help in this case