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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6cf8ea53ff1dd7d8b7e12f852e3fba4b2abdf32dc7f14ea1201d2b92bcf42251' 
  AND token = 'jWrxOWsmqd608CeSoe+AByd+ROnj+rMTvgB7xzWIX8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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