function is_angelleye_express_checkout_used() {
    if (sizeof(WC()->session) == 0) {
        return false;
    }
    $paypal_express_checkout = WC()->session->get( 'paypal_express_checkout' );
    return isset($paypal_express_checkout);
}
add_action('woocommerce_before_checkout_form', 'angelleye_woocommerce_before_checkout_form', 9);
function angelleye_woocommerce_before_checkout_form() {
    if(is_angelleye_express_checkout_used()) {
        echo '<div><p>' . __('Sample text before checkout form', '') . '</p></div>';
    }
}