SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16c873e9840b05ce0e0823655100f28b316f5c749e7123369f9150dd2b226422' 
  AND token = 'sCUnNEJHNiOfTCAxSK74qwXmCEhYs9PuL8g8/jFiOX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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