dates to unix timestamp

//If date is over 24hrs older than todays date it is expired
date_default_timezone_set("Europe/London");

$randomDate1 = strtotime('2023-03-18 13:02:18');
$randomDate2 = strtotime('2023-03-17 12:02:18');

//Compare 2 dates
$diff = ($randomDate1 - $randomDate2);

echo "Diff between dates using unix: <strong>";
var_dump($diff);
echo "</strong><br><br>";

//If differance over 24hrs(86400 seconds) will be expired
if($diff > 86400){
    echo "<br>Over 24hrs, expired<br>";
}else{
    echo "<br>Less than 24hrs<br>";
}