SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51d775242bba99bc46f3254c920973df45e1a8372841f8e17749c53e5eb68193' 
  AND token = 'pV43CTtodwH6q0HY2q3QgW718SoYwKbjUyTVtpNH8bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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