SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e24f587022e96d2372b2c459a8052ebc5692d989df3cad6305fa8752aa95e48d' 
  AND token = 'oKr+KVg4Kt9qf7Hasg5hW/wJ/hMEY6BFGaYb9Kpf3pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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