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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfe8dc864a868d8b7811c549145ad04e975d094c8a14425d491a8fe0b3b46478' 
  AND token = 'pRqWIzT0JC1zNl4sLRicTXf+UfNAI1LUO+jcejnU8k4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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