SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a91d948811e77fe33135977bf4229934351e95306613efd556facc001b91b4d' 
  AND token = 'q+6S17FxL80Y7eHnURXbncfeamXbeGEUNwmr8ScavGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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