Build a lookup hash:

#!/usr/bin/perl

use warnings;
use strict;

use Data::Dumper;

my $array_ref = [1, 2, 3, 4, 5];

my $array_of_hashes_ref = [
    {key => 4, name => 'label4'},
    {key => 2, name => 'label2'},
    {key => 5, name => 'label5'},
    {key => 1, name => 'label1'},
    {key => 3, name => 'label3'}
];

my %lookup;

@lookup{map {$_->{key}} @$array_of_hashes_ref} = @$array_of_hashes_ref
+;

print "$lookup{$_}{key}, $lookup{$_}{name}\n" for @$array_ref;
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Prints:

1, label1
2, label2
3, label3
4, label4
5, label5
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