SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16daf0387059c57926b8c1448642f480828b0988b36ef924474f27fe11aae536' 
  AND token = 'UHolMK1pqq8upp3bQHm623aB2+bSjmaF//25tHdQjHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

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