SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c753385260b8ac0e1956d1237a01280751296fdf4480e5faff8ac4898a5ec63' 
  AND token = 'xAJXrmdKni+eFJ9IMNBXeQ+f/gm9uPXJQH03GkPQAl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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