Windows forms - Detecting when a key combination is pressed

I am building a WinForms application and one of its functions is to perform an action when a key combination is pressed. I know how to detect when a modifier key + some other key is pressed (for example Ctrl+S, Shift+A, or Alt+D). The problem is detecting when a key combination without a modifier is pressed, for example A+S, W+X or Z+Y+D. I have tried using KeyDown and KeyUp events, KeyPress event and ProcessCmdKey but all of them seem to only be able to detect one key press or key press + modifier key. Is there some other way of detecting those key combinations?