SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acd0d475a85a30f452983d67bde328e529f57d2a276a56f722f3a390bb97c226' 
  AND token = 'Eijhbsb9QQw9XjtWrveO6w5cLgiCFDl+/dCszV0Xcro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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