SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '88732af87455bcef737dcbffaba5544e43b5c5bbf2457a6764837f351dd8723d' 
  AND token = 'chLD9qwGIkHp9XVQBTmWIpaAn/YimT24QsA8jurEYvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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