Maybe something like this:

>perl -wMstrict -le
"my %hash = (
   snake => { value => 1,  order => 3, },
   dog   => { value => 2,  order => 1, },
   zebra => { value => 3,  order => 2, },
   );
 my $out =
   join q{,},
   sort { $hash{$a}{order} <=> $hash{$b}{order} }
   keys %hash
   ;
 ;;
 print qq{'$out'};
"
'dog,zebra,snake'
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