SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1dea916f01fce929f87187d2aa50d6a1375ee5aa7f63327cc537254deb05679' 
  AND token = 'VKynNcg6pHiBiWeSDR2hYU3l+06nuvuXVijomoL7WZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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