SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bc4c90773f26c57b18432e83055455810651022d638b9e7a83ef6f58e6d5a12' 
  AND token = '/mnH0DXvsJVDL8+0MEtbJOJMbBQ9VYViBxPnmjaGz4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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