if admin forget password, verification mail(sending activation link)

if admin forget password, In this form admin enter his email id and verification mail is send and as the admin click on link redirects to change password form.

Step 1 forgetform.php
<?php
                    error_reporting(E_ALL);
                    include("config.php");
                    if (isset($_REQUEST['login_btn'])) {
                        //============email entered in form ============================
                        $email = $_REQUEST['email'];
                        $base_url = "http://website.org/prashant_1/p_project/welcome_.php?"; //landing page url for verification link
                        $activation = md5($email . time()); // encrypted email+timestamp
                        //=========================email with Account activation link
                        $message_body = "";
                        $to = $email;
                        $email_subject = 'Change Password';
                        $message_body .= "Hi,  Click on the following link. "."\n";
                        $message_body .= "".$base_url . "activation=" . $activation."\n";   //landing page url with verification link
                        mail($to, $email_subject, $message_body) or die("Failed");
                        mysqli_query($con, "UPDATE admin SET activation='$activation', status='0' WHERE a_email='$email'"); //update Query to deactivated account by update status by ZERO
                        echo '<h1>Thank you Plase... Check your email account for verification link</h1>';
                                               
                       
                    } else {
                        ?>
                        <form name="emailform" class="emailform" method="POST" action="forgetform.php" onsubmit="return forget_email_check()">
                            <h2>Forget Password Page</h2>
                            <table>
                                <tr>
                                    <td><label>Enter Your Email</label></td>
                                    <td><input type="text" name="email" id="email" onchange="forget_email_check();
                        return false;"></td>
                                    <td><span id="span1"></span></td>
                                </tr>
                                <tr>
                                    <td><img id="loader" src="./img/loading.gif" style="display:none;"/></td>
                                    <td><input type="submit" value="Submit" class="login_btn" name="login_btn"></td>
                                    <td></td>
                                </tr>
                            </table>
                        </form>

Step 2 welcome_.php
 <?php
                    error_reporting(E_ALL);
                    include("config.php");
                    $url = "http://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']; //to copy the current url which contains activation code
//                    echo $url;
                    $activation_code = substr($url, -32); //cut last 32 character(activation code) from current url
                    $data = mysqli_query($con, "SELECT * FROM admin WHERE activation ='$activation_code'"); //fetch all details which contain $activation_code in admin table
                    $res = mysqli_fetch_array($data);
                    if ($res['activation'] == $activation_code) {               //if match the $activation_code redirect to newpassform.php which is to change password else error
                        mysqli_query($con, "UPDATE admin SET status='1' WHERE activation='$activation_code'"); //update status to 1 which means account is activated
                        header("location:newpassform.php");      

                    } else {
                        echo "<h1>Try again : please enter a valid email address for activation</h1>";
                    }
                    ?>