SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7acbb639b04df12b4b84d85fc77983c1577f24bd61607cdcf2778fa34de8acf' 
  AND token = 'DORLwGMug9jy1f3T+yVtWeBTGqSz7JQg+/NTbSQVZkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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