Limitless objects with each size upto 5TB are stored using S3 bucket in AWS. Buckets allows to store objects that are related to one another. 
Amazon S3 having the object search box in user interface  to allows you to search prefix or you can use Amazon S3 API's LIST operation, which only returns thousands of objects at a time.
To resolve this issue we have to build an external index and search for S3 object.

AWS Command Line Interface (CLI) is the best way to find a file in an S3 bucket. Type the following command in terminal window for file search 

aws s3 ls s3://bucket/ --recursive "filename"
aws s3 ls s3://bucket/ --recursive | grep filename

recursive: performs the command on all files under the set prefix