SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6d23fefc270092be0babed0f6091550e637a87f193d2269a737690cb52faa55' 
  AND token = 'USFDGYDtjNXyb2NqP/PpzQbAUgRW09D9RO5tmV78KTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables