require_once( 'wp-includes/class-phpass.php' );
$wp_hasher = new PasswordHash( 8, TRUE );
$password = "passwordhere";
$hashed_password = $wp_hasher->HashPassword( $password );
$encryptedpass = md5($hashed_password);

SELECT * FROM wp_customers WHERE email = "ccc@aaa.com" AND password = "<what goes here?>"

function wp_check_password($password, $hash, $user_id = '') {
    global $wp_hasher;

    // If the hash is still md5...
    if ( strlen($hash) <= 32 ) {
        $check = ( $hash == md5($password) );
        if ( $check && $user_id ) {
            // Rehash using new hash.
            wp_set_password($password, $user_id);
            $hash = wp_hash_password($password);
        }

        return apply_filters('check_password', $check, $password, $hash, $user_id);
    }

    // If the stored hash is longer than an MD5, presume the
    // new style phpass portable hash.
    if ( empty($wp_hasher) ) {
        require_once ( ABSPATH . 'wp-includes/class-phpass.php');
        // By default, use the portable hash from phpass
        $wp_hasher = new PasswordHash(8, TRUE);
    }

    $check = $wp_hasher->CheckPassword($password, $hash);

    return apply_filters('check_password', $check, $password, $hash, $user_id);
}

function my_password_validation( $username, $password ) {
    // Select the users's password hash from the database
    $stored = query( 'SELECT * FROM wp_customers WHERE email = ' . $username );

    require_one( 'class-phpass.php' );
    $hasher = new PasswordHash(8, TRUE);

    return $hasher->CheckPassword( $password, $stored );
}

<?php
include_once($_SERVER['DOCUMENT_ROOT'].'/wp-includes/class-phpass.php' );

// prepare database connection
$ip_address="localhost";
$user_db="userdb";
$pass_db="passdb";

$conn= mysql_connect($ip_address,$user_db,$pass_db);
mysql_select_db("dbname",$conn);
if (!$conn){
            echo "Could not connect: " . mysql_error();
            exit();
}

// wordpress' username that his password going to compare
$user = 'test';
$user_name = htmlspecialchars($user,ENT_QUOTES);

// plain password to compare
$password = 'tespass';

$hasher = new PasswordHash(8, TRUE);

// get user_name's hashed password from wordpress database
$queryx = "select * from wa1gty5f_users where user_login='$user_name'";
$Resultx = mysql_query($queryx,$conn);

while($row = mysql_fetch_array($Resultx)){
     $passnya = $row[user_pass];
}

// compare plain password with hashed password
if ($hasher->CheckPassword( $password, $passnya )){
    echo "MATCHED";
} else {
    echo "NO MATCHED";
}
?>

<?php

$wp_hasher = new PasswordHash(8, TRUE);

$password_hashed = '$P$B55D6LjfHDkINU5wF.v2BuuzO0/XPk/';
$plain_password = 'test';

if($wp_hasher->CheckPassword($plain_password, $password_hashed)) {
    echo "YES, Matched";
} else {
    echo "No, Wrong Password";
}

?>