SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b4efda7f1cb497993cb8267a4ee7c0bad992878c62ac033fd1dc9ed3bd5cd71' 
  AND token = 'qpvV2/RL/7TZS9Wy5u6lBZvW+m87mlGpUfvB+5h/1sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}