SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e78d8cb6445e0522bc03e8e77a0556d057b812b3703f3fe3798ad65cdabd5400' 
  AND token = 'Kmxu+SDABWCprKhYz+w+yn35+FZhfLJc/llA12sg7OE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}