SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3d2e956ec14167b1c587e8fcf7c196129b9d6baf2e46a2ddf80aa2535fd6f10' 
  AND token = 'UydTUQYZcKtMSKGbECGqUuB1Uy6hm3k/x1J3U50Um2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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