To launch an Elastic Load Balancer ( ELB ) with an existing SSL certificate using Terraform, you need to specify the AWS certificate resource id. If you have already uploaded the certificate and attached it to an existing load balancer, the following AWS CLI command will display it in the command window. MY_PROFILE is the name of the profile in the square brackets  in the ~/.aws/credentials file.
aws elb describe-load-balancers --region MY_AWS_REGION --profile MY_PROFILE |grep SSL
To get all information on the load balancers, just omit the grep command:
aws elb describe-load-balancers --region MY_AWS_REGION --profile MY_PROFILE