SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31ceca90a48e2133fe3cc8f478b36e58c977f32aa114a230e27662f6e7501d31' 
  AND token = 'UsHlHoZ2QvCqDI+yryT2Srs9dSFFOyrajn/qMXsOi8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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