SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd28c5b48cb5588745ae360021c641d575d5643af277097428f1f69394c14e352' 
  AND token = 'ANvgXAPVRbIezvyd1Tr2/8Pm/wLZxEHckr1JXZmDguY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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