SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfa01d6288ba910f93364e51d1eda7e828abd3b3fca2fbcaddd955c4c9e7e20b' 
  AND token = 'bDgDBgntsee3cArxnvWoqWN55zFXb1PN0ZjUuRVNPf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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