curl --request GET \
  --url https://iris-api-sandbox.circle.com/v2/publicKeys

{
  "publicKeys": [
    {
      "publicKey": "0x04fc192351b97838713efbc63351e3b71607cc7fc0a74fadaa12d39a693713529bf392c0eeaff62eff2f06b47a4c7cd5f83159e4145444f817d5e7f24e256c6278",
      "cctpVersion": "1"
    }
  ]
}