SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd84489560b78573c57a64997f1f81614a85283528106e044818d8159d3a8f12' 
  AND token = '1AkbAnE7tAUb9AduxBDBl7QtueBHBV8touXgalcfwvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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