SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e25c1342910c78d1977d103424702169adb250f42bbee30be20d6a5b3d2c92c' 
  AND token = 'fUY1Bg/Vr+hIFmoylRALLKVt6tAa1NvmN0vqBzDYG/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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