You can do the following:
set -- xorg-x11-fonts*
if [ -f "$1" ]; then
printf "BLAH"
fi
This works with sh and derivates: ksh and bash. It doesn't create any sub-shell. $(..)and `...` commands used in other solutions create a sub-shell : they fork a process, and they are inefficient. Of course it works with several files, and this solution can be the fastest, or second to the fastest one.
It works too when there's no matches. There isn't need to use nullglob as one of the commentators say. $1 will contain the origintal test name, therefore the test -f $1 won't success, because the $1 file doesn't exist.