SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '257496a01cf60656cc1024e506fcc2ce3af1ae8cd3374c98dd1a7bafe3ff897d' 
  AND token = '+KDc2q4x6pq/Vk2SPgM+NLh2+t5XhIfY8F/FA3TPf8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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