SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5821779ba89d0b95a3498242f218f3a6be44438dd0a52fd1916af3544a54e9b' 
  AND token = 'njpLTipZiiqlyujnHw/JPkueOuF6FxALPhp7MTKA32Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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