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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'aee9768fa396b72e7db33339ef02903378b275cb075e2a6332975fd359662d26' 
  AND token = 'CMU3jcwRRFnTwp74LUVEyjWH5ZhmUeneXxvELCjWllY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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