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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '271569442d6fec18b18b6672b6604c75b42eb1af15ea9ec75fbba0ab9bd3242c' 
  AND token = 'GcChf/eyw/ECSh+gLN9pljFteEk3Vx4tIcLbn/+0aCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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