SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '523ef20e75b855139583ea320e74da81c8b5e826f09a6c3449da7791aea5bedd' 
  AND token = 'yGVXViT+KAuCZazOqtZ35QXE5VPQ3NpnvYwzOrprjDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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