The console key is tilde "`" which is only in EN_US kb layout.
If you want to change it, go to %LOCALAPPDATA%\Insurgency\Saved\Config\WindowsClient
Open Input.ini in text editor of your choice.
Add these lines to said file:
Replace "Semicolon" by any key you want, though you have to name the key out like in this example (full name of the key rather than the symbol).
Save it, make it read-only via its properties and boot the game.