zcash_keys is used at run time in 5 crates (of which 2 optionally). It is a direct run-time dependency in 3 crates.

Depender (with downloads and own rev deps) zcash_keys version
900 4 zcash_client_backend ^0.4
550 zcash_client_sqlite ^0.4
110 zebra-scan ^0.4.0