APR is an Annual Percentage Rate, which is calculated over a period of the whole year. That is why at the first glance the APR applied to payday loans seems to be high. This is not true because a payday loan is taken normally over a number of days or a few weeks.
The APR was calculated for long term loans which are usually taken for a year or more. It was not designed for very short term loans. It is just a theoretical figure that helps people compare similar long term loans such as ongoing credit balances or mortgages.
So instead of worrying about the APR rate you had better take another look at your loan agreement and see how much interest you will have to pay for the period of your payday loan. Sometimes it's a standard interest charge which depends on how much you want to borrow and it doesn't depend on the duration of the loan. So you should consider whether you will be able to pay both the cash advance you get and the interest pay on the repayment date.