in src/dotnet/AzureAI.Proxy/OpenAIHandlers/OpenAIAccessToken.cs [23:31]
public static bool IsTokenExpired(string accessToken)
{
var tokenHandler = new JwtSecurityTokenHandler();
var jwttoken = tokenHandler.ReadToken(accessToken);
var expDate = jwttoken.ValidTo;
bool result = expDate < DateTime.UtcNow;
return result;
}