SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36e1d344dd3370c5bb6bf51baf9e69f52cb671d3ff39c0f944583471b25c48b4' 
  AND token = 'gQVTfBHuuEwfe+QoUruNr1HrQKpJfgjSccMoIyNAp7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}