SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '146d2a6be293bda6bbebf6973a40f9ed9093d373e031cff3f62177cb0062f023' 
  AND token = 'KGpKy8KoF/tXjJECClnRDAGznxTyhFxLWZFlVBcZThY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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