SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eae0cc4a69d00ae1b6815940796ff3fafd9437ade95c2b88c97e752728d020ef' 
  AND token = '9339wQAxWhGZm9lBkByNzk57D03rP6toSkuUxvWsKB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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