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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3560d26f6d19673661b6dc5ed5b0064fdc79ba0d5fb3a171c721d9b6f3b3a4a' 
  AND token = 'uV3+KM3vXED4eJoLkpiFFAH9ThurEPTuN+a9V4qSnQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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