SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47ebf3460c389bb9418f72586aec19f69bb099d8a59afb0a3e5537555697ae61' 
  AND token = '6LKkxpS9yEr2db+6nAQ3uenzNUyGCH0vj2u73ohrMcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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