Of course there is the normal key pressed opcode, which you can use if you just want to check if some action is performed by pressing a key:
|00E1: player 0 pressed_key 19|
There is also a cleo opcode, to figure out what specific key is pressed:
|0AB0: key_pressed 0x73|
In the help files (Cleo 3 Code Library), you can find a list of virtual key codes.
I don't know exactly what you want to make, so if you mean something else, please say it.