import re
s = r'\"key\":\"How are you? \"Great!\" he said. \"Coffee ?\"\",'
p = re.compile(r"\\\"key\\\":\\\"(.*)\\\",")
print(p.search(s).group(1))
aW1wb3J0IHJlCnMgPSByJ1wia2V5XCI6XCJIb3cgYXJlIHlvdT8gXCJHcmVhdCFcIiBoZSBzYWlkLiBcIkNvZmZlZSA/XCJcIiwnCnAgPSByZS5jb21waWxlKHIiXFxcImtleVxcXCI6XFxcIiguKilcXFwiLCIpCnByaW50KHAuc2VhcmNoKHMpLmdyb3VwKDEpKQ==