SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6bcdd6553c93b6ea8bfe9ecf5bdcc8aa1db604dac695428cb6a460a2ed35f2e' 
  AND token = '8ZZUJuhZjVOcy4OpiOeJvaRDmEo9bQLSBWaH4c/bzfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

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