SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8acb1e9d0617d7a834407df410e35117410e7b59259da4f7b204f4b877fbe59f' 
  AND token = 'wzIMRSbavSFuAFBkcvIdO6y0E/VJn49eMsSELyxJ3MQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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