SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4d690f7050178571e40f4faad15e98399a99b8bae66e022f909ac673f486549' 
  AND token = 'QSXcZ2LwQm9IbWkUnnDVrTD4EaYXE1h1UIOgv/rrngY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

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