SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38ffeadeae387595370fb333b938e2512368380adce94278297ed66daf018afa' 
  AND token = 'g+a379A45FWdTyxdD/gAHehxPTPcjMqVv5vscrcK5js=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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