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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '13f759d0de6d898f37ff60e4c8a4452b6af1d79e3384e453f4ea8e76a3b057a1' 
  AND token = 'wkh2WBQGnWiHkOLCzMQ4S6AEWl1gbio0PHfjc7BvjJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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