Get claims from ExternalAuthSecurityToken

[maordadush]

Hi,
How can I get MFA claims from securityContext.UserToken in EvaluatePreAuthentication method?

{Microsoft.IdentityServer.Service.ExternalAuth.ExternalAuthSecurityToken}
Claims: Count = 8
Id: "_36d6901b-c078-4e30-8be0-c50e031c49fa-B3D62E6F308444A4E54540BC64495EEA"
SecurityKeys: Count = 0
ValidFrom: {10/10/2019 2:56:50 PM}
ValidTo: {10/11/2019 12:56:50 AM}

Thanks!