To check if your OpenAI API key is valid, you can try making a test API call and see if it works without any errors. Here's a simple code example:

import openai

openai.api_key = 'YOUR_API_KEY'

def is_api_key_valid():
    try:
        response = openai.Completion.create(
            engine="davinci",
            prompt="This is a test.",
            max_tokens=5
        )
    except:
        return False
    else:
        return True

# Check the validity of the API key
api_key_valid = is_api_key_valid()
print("API key is valid:", api_key_valid)

Replace 'YOUR_API_KEY' with your actual OpenAI API key. The is_api_key_valid function attempts a simple test API call. If the call succeeds without any errors, it means your API key is valid, and the function returns True. However, if any error occurs during the API call, it means the key is likely invalid, and the function returns False.

By running the code and checking the value of api_key_valid, you can determine if your OpenAI API key is valid.