SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b707fec89a9eef08c93f17b26b3639289a859bf56843ed6071342072f71ebdcd' 
  AND token = 'MqnVUpiJ6i/sZcZfwyUuv2mXW4x7+2vJuwEnncrTY3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}