SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dae0384825f2fb0eed96930f420a1ac16613fe86b435d94406434026ebf7c64' 
  AND token = 'bQzi+dogn+UowUMTLzigbY3LJDpineKU71GLi6OZiCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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