SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd172389e5dc4da9e94aed726819182316149151d87ff61f68750740df169d16' 
  AND token = 'tELDdRYlxfxv3eBoHh+YEWpz5mzMRfFB2nfq1KOU/TA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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