SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6842d3f70b7b9fe3e504631e8d8861fc64a13b59554612e2894ea0b4006f672d' 
  AND token = 'wMc2GGGjazTOqf+8liRjpGye9iBJRyN7gFHZ+AG2gpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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