SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '877670818615c164048a94ee00a8dbd04f2ab50f0a755f45868c97d61662ba45' 
  AND token = 'd5VZ54JEmDa4PKf3/JSVAhsa+v9Pgp3CjcMzXBM8JCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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