SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a57da07d10897b5f940ddd0665f2e20288873098cee6eead39e724783be75321' 
  AND token = 'IqW6Vr+2eTrSmZGYtEb+PXjJ+PBRyw/8SLrFo+WowQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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