SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '274a35c584f968255cba109f0257d9f1970847efe89e28bf45945e7562cc598e' 
  AND token = 'VifxRFgg5u6cK4/5YiGB8YAgPBENsI67FkAdECb5tMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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