In the context of testing an AWS Lambda function, which of the following JSON payloads is formatted correctly to serve as a test event that would trigger the Lambda function?
{"key1": "value1", "key2": "value2"}
{"key1": "value1" "key2": "value2"}
{"key1": value1, "key2": value2}
{key1: 'value1', key2: 'value2'}