Most things on the Mac OS that used Command will use Ctrl on the PC. Things on the Mac OS that used Opt will use Alt on the PC.
solution is between something like alt+shift+p or alt+ctrl+p,
in fact, I've edited the shortcut file and put the mac equivalent : alt+p and it works
the file is in the folder user/nameofuser/appdata/roaming/adobe/after effects/12,2
it's a text file with sortcuts
you can edit with something like notepad
See the table of keyboard shortcuts in After Effects Help here:
The entry that you're interested in is
"Add or remove keyframe at current time".