SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb259e8ffd956682de315ec48c8b7ea387436ec1794b671494ea8e586a8479eb' 
  AND token = '9TH9uZ4qOthHp/8hqg73bqd+x/Z/wBR0S9mPKCQCk2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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