SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9d6f41f862c19b7afee99e6e53d08c24043bcaf7b867f93c94ea33271a4a698' 
  AND token = 'DAKiUFLz/xKSakvSVlt9cCGqKuvb3B8RTPJvG6F0ZEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00082

JSON explain

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