SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bbeb854d1568417ca41e43dd85aacb1f2a15fcf26a9f9b15da051731396b406' 
  AND token = 'xd7v5v3+sfDi5LPKeM4GYYsjTWVN5wFirJqh1H7g5Ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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