use List::Util qw(any first);
my %haystack; @haystack{'aa'..'ff',"0"} = ();
say any { exists $haystack{$_} } qw(aa bb cc dd);

say any { exists $haystack{$_} } qw(zz 0);       # OK
say !! first { exists $haystack{$_} } qw(zz 0);  # Oops!