SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f6d51362bf091833d0f9a447b8904ce4149a92e2ba13186dcc4764d1efd39585' 
  AND token = 'k3cUGwWm5szj2Gx9g4cHCRHlwsILqHyviffc1oRppns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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