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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1248400a1e708d710dd294efc784b43d6fed7fb5fd5b514860b4dde633f36fcb' 
  AND token = 'ONUnDlCEaFaVfDnXBlB38UmSogdhLEn6kRPQho4tm6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}