SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923be71d38afcfb7c70af370a38790441751ea0a3eff240be88688df986d956c' 
  AND token = 'Y2bJuW43tmM+U6TaL9NzWwwkIMc+zTvCAiiUuPEsOm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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