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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a70f8daf5f35d9e6e581a89349117a37c8b4e59fdd1393bfafa7a1d364231518' 
  AND token = 'PRKGOuWXTXb7ExOFCwYsKh15Y1v44F4cbx36Tgcg7uM=' 
  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"
    }
  }
}