SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9209bbefee6cfb65e7329b9c8a9dea4121d354bfec01feec4daf3586bbd91c3e' 
  AND token = 'quR4Ry3WzHUxJusSIvRJdzpaH5DaDkrLK6fCSb2hLzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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