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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1e2f2fb32e6a0efdafcb6ac656d253a5e899a3fd88803cc7d29ac921ae92c513' 
  AND token = 'VKBJbBDGMkRJttBvk2Vmz9ZHMT7gkBMAFPAfk/H3xsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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