Connect to MySQL database from Lambda function (Node)

Since you're using RDS, go check out it's security group configuration. By default RDS's security group will allow inbound connections from your own IP and your default security group on your default VPC. However Lambda, by default, runs under no VPC, and thus is not able to establish a connection to RDS.

Either change your RDS instance to allow all IP addresses, or execute your Lambda function under a VPC that your RDS instance can access, and allow access to the security group.

Increase the timeout to one minute. It could be due to the coldstart of the lambda function.

Only your first call should take time, consecutive calls should be very fast, since you are reusing the same connection.

Also, By having higher timeout, does not mean you will be charged for that timeout, you will be charged only for the time the Lambda runs.

Also to speed up the coldstart time you can webpack your scripts,

http://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/webpack.html

There is one more issue noticed,

var mysql = require('mysql');

var connection = mysql.createConnection({
    host     : 'amazon-string.rds.amazonaws.com',
    user     : 'myusername',
    password : 'mypassword'
});

connection.connect();

exports.handler = (event, context) => {

    connection.query("SELECT * FROM table", function(err, rows, fields) {
        console.log("rows: " + rows);
        context.succeed('Success');
    });

};

Hope it helps.