Your code *does* work. What makes you think it doesn't?

<your code here>

require Data::Dumper;
print(Data::Dumper::Dumper(\%hash1));

__END__
output
======
$VAR1 = {
          'key5' => 'value5',
          'key2' => 'value2',
          'key1' => 'value1'
        };
[download]

Of course, you should quote key3 and key4 (it's good practice, and it's strict-friendly):
@array = ("key3", "key4");
or
@array = qw( key3 key4 );

And why use
"$_"
when you can simply use
$_