SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '257a289a489a01585dba2ab336dccb9f7afdd355ebf9350089d0d2b007547706' 
  AND token = 'yi4vV0nILUNHB5qt7y2vugXKZB+wjcRI004kpUTY9GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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