SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c39142cb2f47f9068cd33d027fa45b5fe4ecc4e80b66f3bca3dd1fd2a63e9383' 
  AND token = 'ofbBzWcwYz0VvS2+CSEFadh1Ok7qVpUNmhXm/9gTC6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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