When I have a “chain of keys” to work through, I sometimes use a loop ... something like this (untested) example:

  my $found = 1;
  my $cursor = $hashref;
  for my $key ( qw/$key1 $key2 $key3/ ) {
     if (exists( $cursor->{$key} ) {
       $cursor = $cursor->{$key};
     } else {
       $found = 0;
       last;  // NOT FOUND - QUIT LOOKING NOW
     }
   }
   . . . 
   if ($found) {
     // $cursor REFERS TO THE ELEMENT THAT WAS FOUND ...
   }
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I hope that the approach is fairly self-explanatory.   $cursor advances through the data-structure (hashref $hashref), $key by key, as long as the keys being sought exist.   Anytime a key is found not to exist, the loop ends early and $found becomes False.   If the loop completes and $found is still True, the entire chain of keys exists and $cursor now points to whatever’s at the end of it all.