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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a8ccf8d0388a9b6e0f8c9fbc7856467e5a8bb69aa7e84d4f1416d011cdd62abc' 
  AND token = 'PHuTq89n+UFMVrVhfBT4O8vMMsaSp4xTcikRzFOTerU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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