The lowest APR for a credit card which stands for "Annual Percentage Rate" is 7.2% but it's very hard to get a credit card with a 7.2% APR unless you have a good credit score and a good credit card use history.
Your current credit card company may lower your annual percentage rate if you've been with them for a long time and have paid them on time.
Some other good credit cards with a low APR are.
Capital One VentureOne Rewards Credit Card with A variable APR of 14.24% - 24.24%
Discover it Cash Back Credit Card with A variable APR of 14.24% - 25.24%
Chase Freedom Unlimited Credit Card With A variable APR of 17.24% - 25.99%