SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28188442cee1df4607401219d3060629a419c024d920c7016c71784874a47a64' 
  AND token = 'uMjrWJ4EIQziETIiq6MYEfoggLqmbWfkXF+S637Geyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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