SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddcbb3d9c6df3026a841c731656f3a969ed1952e7b18b43995aea5f75dabf03c' 
  AND token = 'HM4thj4/lPeUjiSnxMR+VzPezu0qnP0vG20qPnU/Oaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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