my $as_string = 'startKEY=jdjhjfg8y4uh449845&finish';
$as_string =~ /KEY=([^&]+)\&/;
print $1, "\n";

##</code><code>##

use strict;
use URI;

my $uri = URI->new();
$uri->query('startKEY=jdjhjfg8y4uh449845&finish');

my %pair = $uri->query_form();
print $pair{startKEY}, "\n";