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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '12ce11d5f97efabd7c19149485dc8cf4d75c08f7e6417f0e417e21a71cdb8a2c' 
  AND token = 'Ubp7V56eiJuoZbT5+AK6VAaY9ZyRSQxp+D6APaB5xmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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