SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6bae9a3a8b2d5767ebbba0dc6420168a9aa701547827c24cc01af23a442fe1f1' 
  AND token = 'LSoYAN3bdgZTbg+2fU1NzypXkfLQJUBGPm+QyPUY4ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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