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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '208ebd1680b479c6501c5f7de278db4b8c4d5e14be6e3b114fb9ac30a9f2c35c' 
  AND token = 'JCRyAws4Pw4nktQ08EWntFcwIWCgaNkrJwAdfSKnxNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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