SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '359c5cef4f07ceda4d8519b5f7daf6bf48c1a99b245fa0e91d6343441b46b000' 
  AND token = 'A7tOP4SlA0ich3AOdkDai3vkFmvDVd/b/nnu+tIfWwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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