SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b318a4344b3c68bad60b5f3276d869100bf0a7e3370cf1e761d55a8a2f57879' 
  AND token = 'XzYL8TF5rulcr1iSbHMNwiRO3ymawAbbc9wBbQHNizA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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