Make Link expire after X minutes
<p>Okay I am sending an activation email link to user's email. My Activation  link is working perfect I wants to make that link expire after X minutes.
Here is my code:</p>

<pre><code>$base_url='http://172.16.0.60/WebServices/';
$activation=md5($email.time());
email format to HTML
        $mail-&gt;Subject = 'Activate Your Account';
        $mail-&gt;Body    = 'Hi, &lt;br/&gt; &lt;br/&gt; We need to make sure you are human. Please verify your email and get started using your Website account. &lt;br/&gt; &lt;br/&gt; &lt;a href="'.$base_url.'activation/'.$activation.'"&gt;'.$base_url.'activation/'.$activation.'&lt;/a&gt;';
</code></pre>

<p>Now my
    .htaccess file</p>

<pre><code> RewriteEngine On

    RewriteRule ^activation/([a-zA-Z0-9_-]+)$ activation.php?code=$1
    RewriteRule ^activation/([a-zA-Z0-9_-]+)/$ activation.php?code=$1
</code></pre>

<p>Now how can I make my link expire? I dont have timestamp field in my database.</p>