SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '592b83a4f53ec6e7b0d63b2ebf42eb234f0f3d98401548bb3a934c89ece58cf6' 
  AND token = 'DUpbqYtDnU0JOZxK4nkOL9euCfTOjxDj6SybwHN37nY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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