SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fdd903b8e298d563f10dcb47001ceadee32accd91029e5cd04a75fffc633bfb' 
  AND token = 'L/ZcTXH1ZMRIQ+emoEJ/2464SZqbeL7porcS80Ac9wA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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