This comment has some merit, but FYI there are a significant number of caveats.

1) Walgreens does not offer the antigen test (BinaxNow) in CA. The lab PCR test is readily available, with locations near LAX, but is typically close to 3 days for the result.
2) CVS does offer a rapid result (antigen) test in LA, but at a limited number of locations (none nearby to LAX) and you must typically book several days in advance. The lab PCR test is far more readily available, but is typically 3+- days for the result.