SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7543c711d4a30810a522ea8d20b7d809b62136d815c75727b91771fde434648' 
  AND token = 'PxH1weHVGt9UVJdnm69yq8PMG3F7XCZepRUfkW0/MXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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