SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f1361b029a545eaa8403e63f5634fb3db79cea65ec2f0c433e6a20794cbb46a' 
  AND token = 'KAYCt+tu2QRYEGFW4SlM8L8uW7aGjHF7A8zVohzv+nI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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