SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ff60e762d274b7e9bcc423774a43756b3d62db32ddfc63e1fb637c3ca838568' 
  AND token = '9fpBBUx15MjCjrp6Lq7w+sFDvd80tVkrcIzW2gjshY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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