SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97673b40f936d575cac79b692a6631f76e83b8b43c0d502e77cf18f7f568a073' 
  AND token = '+zQ8bRVKUHAFXN49LNVJ+jj//xUykPCES1aBI8SZx04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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