SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21d723e8a46740a15e59bcfc9be1699b65824a377cd25ee3bb2fb172b03fb265' 
  AND token = 'dx9yLXKTRHXlhE5rw6TezUVDcxDY9Vf2+uZSRinqChw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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