SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d2b763cb27ff473c56ef5d1750d510b669b5f2e28e673da42fe3cd20663e0d' 
  AND token = 'm4wN5ZyVM16bcIirD0ju5aRCM+xO5o8ySxmSQKM/7Zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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