What do I need to configure to connect to my database from my Flask-SQLAlchemy code running on AWS?

I'm unable to access my MySQL database running as an AWS RDS from my AWS EB application and wonder whether I'm missing a configuration step to make this possible.

I've confirmed that

application.config['SQLALCHEMY_DATABASE_URI']

in the instance running on AWS corresponds to an endpoint, database, user name, and password that exactly matches those I use to successfully connect from my remote machine using my MySQL admin tools, but I still get internal server errors when I attempt any database operation from my application.

Are there additional configuration steps required to be able to access a MySQL AWS RDS database that from within my EB application (beyond or other than those used to access the database externally)?