SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '866df382c0c88e204081602b1e320fc678f9680fb0d4793a12ea411fb853f795' 
  AND token = 'LUPlVgpsB47jCz+pXrgnvPZB7QygdE3umYlExCwX5Rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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