SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca8c8aa8953a04e36a7a0f18bfb32631f9298d586597a2f6fdff6332e155d230' 
  AND token = '91FevRKJhiuB/NcAM8ph4ZXQ7B1kMjlUSgh4tjQ5Y+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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