SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100a73405dd74450616f954c021d9336cf0e609323a5d61679cec05ddd080e7f' 
  AND token = 'j5l6mkHRrIyhE2dqR1JZueSvWjdrqKhSv3Jk137AqyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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