SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8398ba5de97ce90705a74b23c61dcfe69e29cf67276bdbd20c431646c08f12ac' 
  AND token = 'yfdamOtRi5tvMqzLJjVxbpCvTpOBGM1KRom+y/ZoWAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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