SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f5a246c67fb51cb68b07a7f238332cf05593c5557b5740613894d35a6739a28' 
  AND token = '4IavCg0QqavSZOk+cw8Zwsp6/YlqxsHemYbuvA8zOV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

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