SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b21f51ebc4acf12928daf86ab0c61531ceb60210a571cf787280921ea931d5' 
  AND token = '7SXb1nWoU6z09VWb2ZAqGruG9AwH/GlGd6/iNwvJCak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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