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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9c942d8cf3c0d95ed659e3a64cdad77835b29cbd57e859f59b38b363bb50808e' 
  AND token = 'Waxgu+s/1FIdb65QrBrQ5OE7H2OGMN7kR0d/gTeuLdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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