SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff9f0890a754b886186a40ed7d1fcc5244f292120b3b4eaec1cc54ab6903494' 
  AND token = '/u63/JmHXd/jtWAzwv1kCBVIiB5Cw5I/dY2SndzbzOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

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