Como dizer "Caixa Rápido" em inglês

Yes, "Express line" is also correct.

I wondered why the Wal-Mart express line is “20 items or fewer,” which is a lot more items than most places I know of. [Google - USA]

Express checkout lanes were designed to make your shopping trip a little faster by expediting the wait when you have 10 items or fewer. Nevertheless, you'll often spend more time in an express line than a standard one. Here's why.

Let's say you're in an express line with five people ahead of you and everyone has 10 items each (50 items total). In the standard line beside you, there are also five people but they all have 20 items each (100 items total). According to math teacher Dan Meyer, who took a scientific look at checkout times, each item takes approximately 2.8 seconds and each person adds 48 seconds to the total. With equal lines, presumably the checkout time will take 4:28 in the express line and 4:56 in the standard line. Despite the larger number of items, the difference is pretty minimal. That said, express checkout lines tend to be longer because they claim to save time and people think they can get through them quickly. We also cause a number of problems. [Google - USA]

Bons estudos!