SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '838480a4719c1a9e58f0541aa5999fc4f3b654662641d416d193673830628bd5' 
  AND token = 'JlQ6WyTjXguJYdg2U1lKK2+OPFSiDh1mUIe9fabB7lU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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