SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26a6b0b4c1be3524a43998856023dcf92358871cb922493249eea334130dbe5c' 
  AND token = 'KaJMG28lByegCOer9dqu8QAYJ8HnWtpcyxJLrg3JZ30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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