SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fdbaee59e7aeb395c3a53d734bc3dfbf83f1def4d59864c35866b43f3532f40' 
  AND token = 'xSwHZSBMSaKNRG8EADvhTvWCvfcx8w+cOZI8yudnAOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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