I was going to suggest:

   my @ary2 = grep {defined} @hash{@ary};
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It's tempting to just say   my @ary2 = @hash{@ary}.   But the values in @ary that don't match keys in %hash produce undefined values that have to be weeded out.

Here's a quick demo:

#!/usr/bin/perl -w
use strict;

my @ary  = ('a', 'c', 'g', 'l');
my %hash = (a => 1, b => 2, c => 3, d => 4);

my @ary2 = grep {defined} @hash{@ary};

print "[$_]\n" for @ary2;
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