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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '821c9d8ee18cf920567d1d4c94736c33753dfd93f9170902d3cecf2697c0dc0e' 
  AND token = '82qdMTP9jTmx+qaWQMxci9XefDap0KkYdUESOBkSG48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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