In AWS I have a VPC set up with a Bastion Host. The bastion host is a single EC2 instance with a public address trough which you can SSH to any other server on the VPC.
You can create an SSH tunnel into your Bastion host (EC2 instance) to forward ports from your local machine to the remote RDS instance.
on mac/ linux this is the command (for windows follow instructions in the link below):
ssh -L 3306:myinstance.123456789012.us-east-1.rds.amazonaws.com:3306 your_c2_ip
then you can connect with workbench using the following settings:
connection method: standard TCP
hostname: localhost
This post explains it the method in more detail; https://userify.com/blog/howto-connect-mysql-ec2-ssh-tunnel-rds/