SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd46c31cfdd9236b1e0f7f4185ebaa8f1b4fd2098657d0ee3dda5f69f3ae6211' 
  AND token = 'SznoenlQwsxzY5g4OiHciPovphHtGV2RkL4cHCTZ2JQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00071

JSON explain

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