SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b23ddacfafc2ac9c257c47581328f1f6c248f48aa96de98ccb53909999a6345' 
  AND token = 'rCGyqliUNi4+jIZ5xF0ZWN7ej1QtQW/GGBMhhWvzxzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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