SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a43297b9aac08f7acf4d397411d2098fc3ca9d1cd781b015a36f0cdb871e865f' 
  AND token = '4lpvGy/FUYDkd7DQg1yXdgZ1fyjw5RD5BFA8T+lrnFY=' 
  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