/usr/lib/mime/packages/lyx is in lyx 2.2.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | application/x-lyx; lyx %s; edit=lyx %s; nametemplate=%s.lyx; test=test "$DISPLAY" != ""; description="LyX Document"; priority=5
|