sub dive {
   my $r = shift;
   $r = $r->{shift(@_)} while $r && @_;
   return $r;
}

my @paths = ('key1', 'key2:key22', 'key2:key23');

for my $path (@paths) {
   my @path = split(/:/, $path);
   my $val = dive(\%hash, @path);
   ...
}