SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '568fb9ae5597206e2833e254837631f515dc81ddcdfab4ba89e59697fec50899' 
  AND token = 'eFeUdLtF5p8Bsi/5UZle1VwZlyWMJD87BC7Trp5ltN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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