SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b39bf4639879e5e802a6f9ea72572add1a3ac6311f4ab1f6e6093c8818db7308' 
  AND token = 'oIZZWO40YUg5nEXm1km8EO/ELvsKWXUgBTqLm7whv+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

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