SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a83eb6854ca0b9a4d84de5d9f1f3deb9a097f494dfc87c3dc3d73714b67c785' 
  AND token = 'pTCnt+qp4tjD5BznTga5DwVjiJN0aDnfxbHQoiBUp5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}