SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03a8f75889dea80afa7509969042ef97cd763df2d715791cc847e7dd6ca5e56f' 
  AND token = 'uJyNMAmO2481q/ZVUE3wvScdy4wOk8Mrvj0C8lm2HwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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