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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '83dc9fadca6ea84b43cf4951bdbf275565a336f8933fc8cf03b98f4f7731ba9f' 
  AND token = 'PXUirXlrMdpyqY1tvgZQ2bb8pKM65HhM9wGfMeQiKCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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