Invoking the lambda gets timed out after adding VPC configurations

I am using Serverless framework for creating lambdas. I created a simple Lambda function, which queries from an Mongo instance and returns the response. Initially, I created the Mongo instance with publicIp and made the Lambda access that instance with publicIP. It worked well.

Now, in order to increase the security, I added the VPC configuration to the Lambda. Here is my serverless.yml:

functions:
  graphql:
    handler: handler.graphql
    iamRoleStatements:
      - Effect: Allow
        Resource: "*"
        Action:
          - ec2:CreateNetworkInterface
          - ec2:DescribeNetworkInterfaces
          - ec2:DetachNetworkInterface
          - ec2:DeleteNetworkInterface
          - logs:CreateLogGroup
          - logs:CreateLogStream
          - logs:PutLogEvents
    vpc:
      securityGroupIds:
        - sg-16f9e371
      subnetIds:
        - subnet-883a12fe
        - subnet-3f7b1067
    events:
      - http:
          path: graphql
          method: post
          integration: lambda
          memorySize: 256
          timeout: 10
          cors: true
          response:
            headers:
              Access-Control-Allow-Origin: "'*'"

Adding the above configuration, the serverless deployment was successful. Now when I tried to access the function by invoking the APIGateway URL in postman, I get an timeout error. Here is the screenshot of Postman:

Does adding the VPC configuration to Lambda make it inaccessible by invoking it publicly?