SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b55e85d8a6bdf472c77d3b49d944b34970917d6da3e67010f833456f2d3653b' 
  AND token = '/i3hkN0NdEbnIlfzHKxiUBDMv66gMkOKqqe5MsxVUPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}