SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31fb1167ac270d70af75c05fd63695c407ac32d09325562980b45dd993341e1d' 
  AND token = 'wr0fiwF07FIy6/kcAKMF8SUER6LVVWc9nvCB77TY1SM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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