SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c799cd61985dd7769d2bf69f505519024265ade7af9d7e61f9da3317c3b5ddb3' 
  AND token = 'RyYwXPYow4pXm6jqEbuP/Q32JYzJ2KfPXff+boVSLUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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