SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56d9d4844ced6690100b934a06889e2ee0aa41d727716abccf464d122e4b31a4' 
  AND token = 'cufkRrNggs39/W/1OxUI0DtZDsyhfAY8MT22hs4BAN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00069

JSON explain

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