SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '457ca62708f8a53676b51424dfc11702855775c044265cb652390b1b877a4350' 
  AND token = 'OU7XCFuMGD0AT0BMFiKHlE/DwMGJ93EMYx7numAz7g8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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