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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4bc8f0fc86c42f119d68c99596138e97c3d71aa9fca99d7ef2ab6c1f0f79a4e5' 
  AND token = 'cV8Pf/h7X2eAqEObhv7aG2WtfLAMt3My5Eil+sjZqBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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