SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c570cd8666e79aef5fe862cbe736876bd771561b103b469330414f863ccf5b42' 
  AND token = 'jT1HZ7J0q2kpe4CdZ/bAYWuBbKtMwcnZl8zv30GmWvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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