use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Indent = 1;

my %hash = (
    foo  => 1,
    bar  => 2,
    baz  => 3,
    quux => 4
);
my @a = qw(foo bar asdf);
my @b = qw(baz);
++@hash{@a,@b};

print Dumper \%hash;