SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f064d667bfee9760e434f8e5d9d07c198048610cfb1e019a7a9c6e315f77aa88' 
  AND token = 'Kh9kbxTpnlFRsw0bUZ47pW00AFWV3bIkMpaMMiPxQ5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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