SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dcdd8549398db43b91dd2da4c070ad1804dfdebade6cc6fc1496ae323e07762' 
  AND token = 'YiG5SwilKheG/a8sZknhAJoqPv5qWQLV9DCCoSrIn8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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