Update: Reading liz response I realized that I've done a reverse task to what was asked for.

Here is a recursive subroutine for that:

sub applypath{
  my($val, $index, @path) = @_;
  if(!defined($index)){
    return $val;
  }
  return applypath($val->{$index}, @path);
}
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You might add some parameter checking if you need it and of course an iterative subroutine would be more efficient if you are into optimisation.

By the way I feel that my @keys = qw (1,2,3) is not exactly what you wanted to write as it is equivalent to my @keys = "1,2,3". Read about the qw operator on the perlop manpage (perldoc perlop).