SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c381f0a3f711fa0d4cb80cbed62e71d9e344ef7149b1e022aa73c8b375a75934' 
  AND token = 'rdhDg+HgAOvUkTWq67SZUOykN0dpLYqVJDkrnDRMpwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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