use strict;
use warnings;
use 5.016;
use Data::Dumper;

my @array_of_hashes = {
          'opt' => {
                   'step820' => '0',
                   'step190' => '0',
                   'step124' => '0',
                   'step127' => '0',
                   'step410' => '0',
                   'step015' => '2',
                   'step130' => '1',
                   'step013' => '0',
                   'step715' => '0',
                   'step540' => '0',
                   'step800' => '5',
                   'step135' => '0',
                   'step003' => '0',
                   'step455' => '0',
                   }
        };

say Dumper @array_of_hashes;

foreach my $step_number ('step001' .. 'step820')
    {
    next if (not defined $array_of_hashes[0]{opt}{$step_number});
    say $step_number . " = " . $array_of_hashes[0]{opt}{$step_number};    
    }