SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e79842a7db3ea73dbfcdd14989100a2ca90f87d0fd73156db50768563ca8456' 
  AND token = 'Qz6hRvwnF2ECSPZTb4Lc/1HAPBAAhPTqIAaEtSSg4m0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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