SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c672c57adef6950d69199c82ccdd2e223d98d01556056e0b1dd865fba5a1b71' 
  AND token = 'GpXbhFjDsOhnyNDUp4YgT7vbvGo1MVa0PGem156jDAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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