SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98d718c86df1129e82f243256dcdeb1fd3a7f53136083cdf0c775bb0675de35f' 
  AND token = '0kjFkvYB8XW89wciyOEjNBMDHmDPiPK21Rcy2xfkGs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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