SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20a1a4aba2a38216602533893a8e19d763942ffc9ea267b8b7449514adf49252' 
  AND token = 'yiIyFLlTMZ8JK7GFrIIP15QBUYbjmyP+7DLG4419wXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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