Sometimes we need a quick buy option. It works like, when a customer adds products to the cart then it automatically redirects to the checkout page. You can control that option from 'Configuration' tab.
If you using 'Selected' add to card option
Then use "Direct Checkout Page[for Add to cart Selected]" option.
Or if you are using 'Add to Cart' Button then use 'Enable Quick Buy Button [Direct Checkout Page for each product]' option