SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6de1b00fe41075fcda36b74def56b3f1bbb2f4a2ac21f05032fa2c363ffce00f' 
  AND token = 'rYiZViSbN4N9huR/xOXH051wlR/mFT5j9WrvZL7jjjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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