SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '42d138ba9a47d4280b05cfc2f2d58c744a4e9a3a98f660e6490221112859b8ba' 
  AND token = '20lBVcUHwxiYtKpGrRXhxAYSkfpzcevz58pgGLDTa2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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