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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b65d951f76dcd8ed331dbdec10951c6a359fb7fcc2b97c3eee642397ae03e026' 
  AND token = 'c/LJYmgTFz4DWvxSwfWm1QX68oDq5x17tWhL55k406E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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