SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4b15f0a237e88be9b5c0d5c1566982087f8822ca14caa26d4f5f66a1476b57d' 
  AND token = 'O/a3dPkEUsFjNGp4IKAnHMguUeYLEJHNZ4Bm/GYN2a8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

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