SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43ca54d7d12253bebb68f6554145553dce1db8d459fa2fe36b3134156774f409' 
  AND token = 'gnsmP6Qmylkg2UoNtwiq/MpywTmapenqy7MVr1zr7Ow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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