SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cebed74b197a39037fed4f103264ea97b189e364baafcb19efa7f4ea590fdc3' 
  AND token = 'xq7/tyffYWQ5ihxIzYo59TAgEUKjfGZJyi2nh+w22hU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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