SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5d38950025d2d5c5117a1e8293608747e1f20270efb4ba7a50bf58538544ec8' 
  AND token = 'y/8f+158AHJpNQmU65WeeV6SfKsTAMctvevP/pBzmZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}