SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '532c83782ea588785f34cbbb79956b7060de9f1463d2a05846629b45651fe297' 
  AND token = '1ogYKHgHHkeVHA6jVyL2BbOJZFblVppiWqL9DRmJcz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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