SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73db78936ddcd1365b2d219d70201fdf29ed079b928e3bd6bd4b219b7eafdb3c' 
  AND token = 'PqNnbAR6oQR06hfPa27xoM45dVLT7TaPkWHWyR0yC60=' 
  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"
    }
  }
}