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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5fe9fef7c92cb25ef156523d33f818eb73c9251bf4dbc5a6d4b2f1bd76aff2c2' 
  AND token = 'l7pIO2YovgV+joFpotwmQBSa0HpIixuYDkyOj6gsNBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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