SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '75171d15942c473989c714c508600a8f609454685e7fccfdbc08c9dc13f309db' 
  AND token = 'fp3BJKUDPWnlzyYuKf4GBfGeU+yOR/oSv6ey7jB8gTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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