In Pycharm 4, you can specify shortcuts with
File / Settings / Appearance and Behaviour / Keymap
You can create any shortcut you like, and bind it to the command “Python Console” (search for Console), which has no default keymapping. Be aware that it is possible to have multiple consoles open at the same time (for example if you open one in the debugging window) so this may not always behave as you expect it to.
You can toggle back to the last editor window by hitting escape.