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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '319b817a8a4dba9b76b6a6d1f57c24b7d2e88d9cf5942128b7c7be1da50d6e4a' 
  AND token = 'UP58meMCX89YjdaK8bfM3yvg4dxE0ZRjwy35SThbJno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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