SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c586dd91f1717caff737497efd2ca7fc7d9d0ac65704709c5ab23b834b555a35' 
  AND token = 'nKPIUcnXqz37oZ2RlTYC/rjfsSKcZh9wEJTRT+VPYEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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