SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9447559a4a37683427559460a3278299f641f8e9ef345fabed0e8b81b552ba22' 
  AND token = 'RsLhei8sTdsTmjVazc2TWXrPvphsXp2iRDrgibeRz+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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