SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c0a7cdf6b26f75b879aa1dd857c7701682e013fa8e7c5cfbda8b81599267ee8' 
  AND token = 'B9+zp3J5+jDjnCSPqFzLclnG0vNx6GySmhey7/trGFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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