SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43a3b0c9c5eb17db87f73220d38b7fab37385eeea452007fe9d879d82b46cfbb' 
  AND token = '8//jypaeNFryaS373Y5xuEncZkpfmmIvkgnVc9RmNd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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