Skip cart page for a few products redirecting to checkout

Solution:

I chose another approach and a WordPress hook instead of woocommerce. This is based on this answer: WooCommerce – Skip cart page redirecting to checkout page

This is that code:

 function skip_cart_page_redirection_to_checkout() {

    // desired product id redirection
    $product_id = 1461;
    $items_ids = array();

    // Get all items IDs that are in cart
    foreach( WC()->cart->get_cart() as $item ) {
        $items_ids[] = $item['product_id'];
    }

    // If is cart page and the desired peoduct is in cart => redirect to checkout.
    if( is_cart() && in_array($product_id, $items_ids) )
        // WooCommerce 3.0 compatibility added
        if ( version_compare( WC_VERSION, '2.7', '<' ) ) {
            wp_redirect( WC()->cart->get_checkout_url() ); // Older than 3.0
        } else {
            wp_redirect( wc_get_checkout_url() ); // 3.0+ (Thanks to helgatheviking)
        }

}
add_action('template_redirect', 'skip_cart_page_redirection_to_checkout');

This code goes in function.php file of your active child theme (or theme) or also in any plugin file.

The code is tested and fully functional.