SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b968c52d40376a48d12d75dfc0b5cb72f01305047acee39c4f9eb372801ccd1' 
  AND token = 'LMPB5cjOkTLUJYb3bgPxgGfOd4q+dNm86BRDKTsMNfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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