SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f3a537565eb554ceb4675df434ac544ca58a743aefdef0fd37e415ce8d366f' 
  AND token = 'f3PCkgZiUdTM14p8upYMyRosLW2Z+wc/N3MqpirEy14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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