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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0a4e81ee59bda6f1f4b23dbf51c9b0f3ec5afea21bd73052583a00c79036ff10' 
  AND token = 'cGgYGj5a/eiYpjJSBlxAteGS8avyzdC3QMCSlsCIuGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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