SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08ef513959ba26eae95bc874d5799e159c425f7f8fe81e3ea2dc02f649e8b38c' 
  AND token = 'p9bUzTOpVRQRXxKH1INCc8B6PBu/8QIODg+DC9JWqHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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