use warnings;
use strict;
use Data::Dumper;

my $household = {
    23 => { last => 'Smith', first => 'Mary' }, 
    22 => { last => 'Jones', first => 'Bob'  }
};

my @slice = @{ $household->{23} }{qw(first last)};
print Dumper(\@slice);

__END__

$VAR1 = [
          'Mary',
          'Smith'
        ];