SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b28779c9e5533b463833d3677c0626c8932f082122caa5edcc3ddfa4714decd4' 
  AND token = 'qQsnAtdqeInD2rNFS34IKb45CqTHOViql30G+cIWVTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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