SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c12e51a36db344f1faf4f354cd6cde06b73eb96400bf0a1b8987909976080a41' 
  AND token = '3TzHuw2TC+i6nSSypA/X7MJPXtb6RkKhm0mEcg8FW0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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