How to retrieve key alias for SSL Info in Service Callout

[#1]

I use a Service Callout policy in my proxy and need to define SSL Info. Where can I locate the required key alias? I need it to populate the Key Alias element shown below -

<SSLInfo>
  <Enabled>true</Enabled>
  <ClientAuthEnabled>true</ClientAuthEnabled>
  <KeyStore>myKeystore</KeyStore>
  <KeyAlias>myKey</KeyAlias>
  <TrustStore>myTrustStore</TrustStore>
</SSLInfo>