use strict; use warnings;
use List::Util 'all';

# see below for how to properly create your hash
my %words = (
    foo => 1,
    bar => 1,
    baz => 1,
    qux => 1,
);

my @must_exist = (
    'bar',
    'qux',
);

my $all_found = all { exists $words{ $_ } } @must_exist;

if ( $all_found ) {
    ...
}