ALT-clicking it on the EditDesk.
You can see the timecode and keycode of a source clip byTimecode and keycode are displayed in the clip information overlay as follows.
(a) Start keycode for the clip (b) Start Source Timecode for the clip (c) Start Record Timecode for the clip (d) End Record Timecode for the clip (e) End Source Timecode for the clip (f) End keycode for the clip
Image courtesy of The House