SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '134ef17f311eb462da78da039af0b905052883e9d2274c709e04f98e21621f41' 
  AND token = 'Lu6Ir/z8T+mFMp6zUPnOzvM0ExHtZPaJmSFDChKZNoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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