SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f17d0f31c4d27bf0d59e1796867031c11690af35a9370052337922f0ab0eadb4' 
  AND token = 'VltOYKFwUxdGjpKvOxlYmmOWAUrt/bY8QTX5vzONaU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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