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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0dbd39163d7d458001c20c15121fbb5ab30affc59f444c175ad0dba5519208f' 
  AND token = '6OlSrtNfKkDccQFLt3c0pTs0CcTCcwlUeshxXN9w/Jo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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