SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f94c54aab9a8edfad7e8daed7c1a6ff60247fe04c1677c90c35c55624798df3' 
  AND token = 'WnhMLGJKeJt7uTnYkiog1L2O+DFGVfEEKZ/ZAbrCIXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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