SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '338e4c347a3acc56ea2bd047b6e635578add4268eff408cf683d02cdeec97331' 
  AND token = 'EDrzZzKXE67kWMKKMYheTw+u9lgZDmkOCLPYjvSTEzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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