SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c28cf0f36eee5598afc1c07fcdcdb5ec0e5050889cc268a441736cb533a925b6' 
  AND token = 'lJ7h7YRFMXuErcaGyexSqqjS49tmB1mlndLWPYmk+Zw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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