SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d4dcdd81fd96066c655e732d676045c7a0ab65f431d472a1049c4794446e6d9' 
  AND token = 'jxfQd9QozuNcr1ed8NXjQG4G13JPz87Y61SvPk1Mk+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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