SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec40900581c49aa8003ec646ad2e32f4faaed21e1cd835eb18ddd6b1fe125838' 
  AND token = '2b/eKfeadiJO1OdsrnyAj+ksyraCs+ZSY9Ez9+zS+XI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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