SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '873ba416b96d9d2b527277fd379934ebf9ed3742c1a9c387445576d205113b46' 
  AND token = 'Rf0jGUCNhl8ezHLMB9GuLlfuwXihQ0txHcIr+1yVXts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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