SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b76a357765151f808fcbabfd259a02da691aacddaf26e9c291baac885faa413' 
  AND token = 'HmX/FVQbya/iXLzipb26RHsE/17mgXaAS8jR1e9v2xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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