SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20fe0d3fe782065d9303127029fa1c51fc473f1c46900f02292e27a7656ffdbd' 
  AND token = 'uiokyVXQuLBotXYlnQMxtNQ8dJPhtoVEN/4a/jXyuH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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