SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '352df7e75426af24e31bbc5d328e5a865786533f867be86c422f0f1cecad9321' 
  AND token = 'tZGeahB3pGbDBGI4aoOtufpGDzMaaW5Ns7NgqGGd3fU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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