SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d7d1ac3e52651e740b7ce8099106fc5df6d7f92305b7644bc2899d3379e29a' 
  AND token = '2aZPBUxOGsQzr1q+kNt17G8n/ymPS9y2X4NHYpwBiLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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