SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d05638660ceed66e3391724b330fb1ff6c2c73f6482f58aab46e04f88b9600' 
  AND token = 'V8ZThKlRc4iEgUcqZYCR+FM41KjTwQ9qFW50zibQS/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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