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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e855bbe1c9f91a3fed057cf346ee49dd821ae29a5ee54bf84f62dee27d1a58f' 
  AND token = 'BUk7AhuMc6MvnTw+wh1NxhARMt1TM/h5rx44+ZjFeRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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