SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2557ca3ff4a39ec15eb0ad4a6c421f20386da5268eb73907da499b6aa117c351' 
  AND token = '2bXiSwiAF6xnWpBAnjx8A7JC7kXG14YJSclbATmNfGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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