SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91ac5020d3f714ae45d2adb3479a3c0b1fa616f79e3b404fc5a231c5462a24f7' 
  AND token = 'mB/lyfprPwfA5g3g9sIBRGmhjzPzJ+7yLt5gV4vPk9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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