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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27e637564e4df3a806b8485cb071e9816a299b4aaeea5f8e1989ccdba3658ce3' 
  AND token = 'HhJ+7kUXwGrhVA0p47tGhEruOrNxA/EgVYVGE5TVTCQ=' 
  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"
    }
  }
}