use warnings;
use strict;
use LWP::UserAgent;

my $ua = LWP::UserAgent->new(
	ssl_opts => {
		SSL_verify_callback => sub {
			my ($ok, $ctx_store) = @_;
			my $cert = Net::SSLeay::X509_STORE_CTX_get_current_cert($ctx_store);
			print Net::SSLeay::P_ASN1_TIME_get_isotime(
				Net::SSLeay::X509_get_notAfter($cert) ), "\n";
			return $ok;
		},
	},
);
$ua->get('https://www.perlmonks.org/');

__END__

2038-01-18T23:59:59Z
2029-08-21T23:59:59Z
2022-09-02T23:59:59Z