SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '295301c5df4340e71f76b23b706f006075af69a11b519711908e38fe7e109f5c' 
  AND token = '5Xw2ZIyZWeTGcJsVstnlj+X2/XSg/dPu2a6WL+wxVJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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