SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855d6ffa3473ac2f56d8bf8dcce51c450a6791fdb217085eecd06064a9c17ba3' 
  AND token = 'PDK5ZpW9caMofOzmkhNnqI8djfne1eDLIwsdkTMTEiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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