Retrieve an existing API Key

**This endpoint allows you to retrieve a single API key using an `api_key_id`.** The endpoint will return a key's name, ID, and scopes. If the API Key ID does not, exist a `404` status will be returned. See the [API Key Permissions List](https://docs.sendgrid.com/api-reference/how-to-use-the-sendgrid-v3-api/authorization) for all available scopes. An API key's scopes can be updated after creation using the "Update API keys" endpoint.