SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8d63ad59157bb0820daa5a6850501ca6af5f1773d6df1a068378725c85360d4' 
  AND token = 'LGUzOeN9ot11OdW0wVgCK0pcjwGdoTfqbYKw8U5xvag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}