SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc2f20b55d266912f9fdaa208220293c773995a02e4462dd816e3c6d53fdf633' 
  AND token = 'd0MJrz4HXyUpx7XmLwEgxYWnP6/7PGVj32OBqK4y6E4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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