SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51adb6a3c2499404eefc43e507d9f823f09a10164eb06184faf4d66977ab2b1' 
  AND token = 'GaSx2WjPDxc4IloVzy9uzvvN+I46VJ7/FnFwosMcrkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

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