#!/usr/local/bin/perl
use strict;
use warnings;
my $array_ref = [1, 2, 5, 7, 4];

my %hash;
$hash{join $;, @$array_ref} = 'ashok';

for my $as (keys %hash){
    print join ',', split /$;/, $as;
}
[download]

Prints:

1,2,5,7,4

as you wanted. This works by creating a string that contains the array values and uses the string as the hash key. The split pulls the key string back apart for printing.

This is very likely not a good solution to your actual problem however!