SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c939f887b1833295556084921768b44651a22072edd5a3572c14ebef2782461' 
  AND token = '3MSVnIH1PBDz3QZrsvAsdrAZkM78wyAmJTN4xDtpDHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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