SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c38d2816b9bc7a290bfb941fc83bfce57bc09e6cb4351d24e3d49e18b0fd0c70' 
  AND token = 'V+L5bSgO+7g82mLInYRQoe+SiNCj8VLv87LodgGKGIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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