SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db2b8176c488f1df05a22215111436a19ee2d316a6dc37702221d2731c549f6a' 
  AND token = '3bnF4mKe98cWwEPveNkZknOi5GoVyeARfmEWlAl0TgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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