SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29edc827e54a4bd879afdba538b1e2376bf8dae28e17a4b03cb04f574f7de20d' 
  AND token = 'Fz/hhrrwYolvOcYRfT9EGt+bv0FJ8hCWj7pu2n+Z2K8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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