SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4f543ecf9938c55d7e8a541ab35dce806bf46573d1431c467e7fd5c23a710b' 
  AND token = 'xPxyjMh8usbebAnn+tB0ZVtQYvfYC9ZmjTpu7idgWec=' 
  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