{
  "keys": [
    {
      "id": "A1",
      "key": [
        "2gAwIBAgIQKGZsKfAUzaJHVantyrwVdzANBgkqhkiG9w0BAQs"
      ]
    },
     {
      "id": "A2",
      "key": [
        "swKQYDVQQDEyJhY2NvdW50cy5hY2Nlc3Njb250cm9sfsf2dew"
      ]
    },
     {
      "id": "A3",
      "key": [
        "EyJhY2NvdW50cy5hY2Nlc3Njb250cm9sLndpbmRvd3Mubdwe2"
      ]
    }
  ]
}

String keyDetails = "{"keys":[{"id":"A1","key":["2gAwIBAgIQKGZsKfAUzaJHVantyrwVdzANBgkqhkiG9w0BAQs"]},{"id":"A2","key":["swKQYDVQQDEyJhY2NvdW50cy5hY2Nlc3Njb250cm9sfsf2dew"]},{"id":"A3","key":["EyJhY2NvdW50cy5hY2Nlc3Njb250cm9sLndpbmRvd3Mubdwe2"]}]}";
AccessKeys accessKeys = new ObjectMapper().readValue(keyDetails, AccessKeys.class);
Optional<KeyDetails> filteredKey = accessKeys.getKeys().stream().filter(key-> key.getId().equals("A3")).findAny();
if(filteredKey.isPresent()) {
    String keyValue = filteredKey.get().getKey().get(0);
    System.out.println("keyValue==>"+keyValue);
}