object_exists(Bucket, Key)

# -*- coding=utf-8
from qcloud_cos import CosConfig
from qcloud_cos import CosS3Client
import sys
import os
import logging

# Under normal circumstances, use the INFO log level. To locate issues, change it to DEBUG, and the SDK will print communication information with the server.
logging.basicConfig(level=logging.INFO, stream=sys.stdout)

# 1. Set user properties, including secret_id, secret_key, region, etc. Appid has been removed from CosConfig, please include Appid in the Bucket parameter. Bucket is composed of BucketName-Appid.
secret_id = os.environ['COS_SECRET_ID']     # User <1>SecretId</1>. We recommend that you use a sub-account key and follow the principle of least privilege to reduce risks. For more information on how to obtain a sub-account key, visit https://cloud.tencent.com/document/product/598/37140.
secret_key = os.environ['COS_SECRET_KEY']   # User <1>SecretKey</1>. We recommend that you use a sub-account key and follow the principle of least privilege to reduce risks. For more information on how to obtain a sub-account key, visit https://cloud.tencent.com/document/product/598/37140.
region = 'ap-beijing'      # Replace it with the actual region, which can be viewed in the console at https://console.cloud.tencent.com/cos5/bucket.
                           For a list of all regions supported by COS, visit https://cloud.tencent.com/document/product/436/6224
token = None               # Token is required for temporary keys but not permanent keys. For more information about how to generate and use a temporary key, see https://cloud.tencent.com/document/product/436/14048.
scheme = 'https'           # Specify whether to use HTTP or HTTPS protocol to access COS. This is optional and is https by default.

config = CosConfig(Region=region, SecretId=secret_id, SecretKey=secret_key, Token=token, Scheme=scheme)
client = CosS3Client(config)

response = client.object_exists(
    Bucket='examplebucket-1250000000',
    Key='exampleobject')
print(response)