Best way to test if a row exists in a MySQL table

I’m trying to find out if a row exists in a table. Using MySQL, is it better to do a query like this:

SELECT COUNT(*) AS total FROM table1 WHERE ...

and check to see if the total is non-zero or is it better to do a query like this:

SELECT * FROM table1 WHERE ... LIMIT 1

and check to see if any rows were returned?

In both queries, the WHERE clause uses an index.