SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f9753e01831a00a723ea47cab29abe4a2390da4b843b272b5d3f10b6c034e9f' 
  AND token = 'TgByLltF9HC5FsDGvE1npmBZBRWHenx12voBnoLwv84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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