[I'm not sure I buy that, given that I keep seeing news reports of "Company X is eliminating 10,000 jobs" or "Company Y is consolidating its operations and will lay off 250 workers", and given that every job is getting dozens if not scores if not hundreds of applicants.]
"Mature workers" face considerable difficulties getting hired: 40% of companies will not hire someone age 40 or older, 60% will not hire someone age 50 or older, and 80% will not hire someone age 60 or older.
However, both WalMart and CVS do hire mature workers; at WalMart, approximately 14% of the workforce is age 50 or more.
[They're probably working part-time at minimum wage with no benefits.]
Best things a mature worker can do are: keep skills current, perhaps by volunteering or signing up with temp agencies that offer training; expand job search by looking at more companies and different industries; or start own business.
Age Discrimination in Employment Act (ADEA) covers anyone age 40 and up. Legal action is possible; however, only have 180 days to file with EEOC after the incident of discrimination.