Amazon Athena is available now in the US East (N. Virginia) and US West (Oregon) Regions today and will become available in other regions in the coming months. You pay only for the queries that you run; you are charged based on the amount of data scanned by each query (the console will display this information after each query).
https://aws.amazon.com/blogs/aws/amazon-athena-interactive-sql-queries-for-data-in-amazon-s3/

