SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '878d8dcba94de7ae3b9bf0a3f82593388747fcbbb693815050a2ed3d5f5d6960' 
  AND token = 'Wo/KtJF7ShsLfmCl0Wsi94xPJ9+//mell6aPO2SoK5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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