SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f4956772a6ffcea526724a7dc387a126e098ada0d872ffbdeaa7b3d3132070' 
  AND token = '8WaEYJ+Z9QqMVuNNzLHVw31O3uNG3zmJHFpLPWg9qFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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