It doesn't look like XML to me.

It does to me, unless you're not showing everything.

If not, I guess a RegEx would be the way to go.

No, please don't!! Parsing HTML/XML with Regular Expressions

use warnings;
use strict;
use XML::LibXML;

my $xml = <<'END_XML';
<root>
    <result_summary total_records="594" total_pages="3"
    current_page="1" records_this_page="250"
    download_key="xmxnxnxnxnxnxnxnxnx"
    time_start="2020-02-19 15:50:55" feed_version="1.44" />
</root>
END_XML

my $dom = XML::LibXML->load_xml(string => $xml);
my @nodes = $dom->findnodes('//result_summary');
die "Failed to find exactly one result_summary node" unless @nodes==1;
my %attrs = %{ $nodes[0] };

use Data::Dumper;
print Dumper(\%attrs);

__END__

$VAR1 = {
          'total_records' => '594',
          'feed_version' => '1.44',
          'time_start' => '2020-02-19 15:50:55',
          'download_key' => 'xmxnxnxnxnxnxnxnxnx',
          'total_pages' => '3',
          'records_this_page' => '250',
          'current_page' => '1'
        };
[download]