SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '752bcdefa780377abea97cbdba15b4d53087cd9706da59f6871774d17bf10f24' 
  AND token = 'Xwd/Al+ExXr0L2ICsKjflXYAcZhQfXdsfv65foQhgzk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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