MEPES

require("connection.php");
$loginUsername = $_POST["username"];
$request = $Link->prepare("SELECT password FROM usuarios WHERE username=?");
$request->bindParam(1, $loginUsername);
if($request->execute()) {
    $row = $request->fetch(PDO::FETCH_ASSOC);
    $password = $row["password"];
    if (password_verify($_POST["password"], $password)) {
        echo "Ok";
    } else {
        echo "Error verificando la password";
    }
} else {
    echo "Error buscando el usuario";
}