SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c7dfb769d627ede3224c9becfb714e8692b06a95a0961e65aa780f136b1509' 
  AND token = 'xgKr1FZ6UmtpYM2euVJ/PnW4M1qazwDBel48HbBbvYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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