SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '115a10a136c7a3352c3205b4636d9af1f9cb3c1e3b502bc93f15d6bd010a2297' 
  AND token = 'CU6vPFRA4SKFOeN0lzzYgSE5cQTGNU3wSyg2jFpbe8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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